From top left, clockwise: Mexican-American War was a conflict that ushered the American expansion in its western frontier, paving way for new territories (and eventually states) such as Texas and California; Treaty of Waitangi in 1840 resulted with the establishment of New Zealand as a British colony, symbolizing Britain's rising power and expansion to new reaches, particularly in the New World, where demand for imperial power and trade control increases; The great auk goes extinct, as it falls victim to overhunting; First Opium War catalyzed Europe's imperial encroachment and control over Chinese ports, as the war resulted with Hong Kong's succession to Britain via the Treaty of Nanking; The Oregon Trail opens up to the world, prompting a wave of migration to the American west and later on, a gold rush in California that persisted through the 1850s; The saxophone was patented and released to the public, forging way for future music genres such as jazz, swing, and blues; First edition of the Communist Manifesto was published by Karl Marx in February 1848. This publication would go on to create a revolutionary shift in political ideologies and thought in the 20th century, influencing entire states such as Soviet Union, China, and Cuba; the Revolutions of 1848 ravages European politics, and causes multiple socio-cultural changes, particularly in classical music, arts, and politics.

The 1840s (pronounced "eighteen-forties") was a decade of the Gregorian calendar that began on January 1, 1840, and ended on December 31, 1849.

The decade was noted in Europe for featuring the largely unsuccessful Revolutions of 1848, also known as the Springtime of Nations. Throughout the continent, bourgeois liberals and working-class radicals engaged in a series of revolts in favor of social reform. In the United Kingdom, this notably manifested itself through the Chartist movement, which sought universal suffrage and parliamentary reform. In France, the February Revolution led to the overthrow of the Orléans dynasty by Louis-Napoleon Bonaparte. In 1848, the publication of the Communist Manifesto by Karl Marx would help lay the groundwork for the global socialist movement.

The Mexican–American War led to the redrawing of national boundaries in North America. In the United States, mass migration to the new West Coast occurred following the annexation of California from Mexico, with a Gold Rush beginning at the end of the decade. On its northern border, the United States settled the Oregon boundary dispute with the United Kingdom in 1846, thereby solving a domestic political crisis in the former nation.

Politics and wars

Pacific Islands

In 1842, Tahiti and Tahuata were declared a French protectorate, to allow Catholic missionaries to work undisturbed. The capital of Papeetē was founded in 1843. In 1845, George Tupou I united Tonga into a kingdom, and reigned as Tuʻi Kanokupolu.

East Asia


On August 29, 1842, the first of two Opium Wars ended between China and Britain with the Treaty of Nanking. One of the consequences was the cession of modern-day Hong Kong Island to the British. Hong Kong would eventually be returned to China in 1997.

Other events:

  • July 3, 1844 – The United States signs the Treaty of Wanghia with the Chinese Government, the first ever diplomatic agreement between China and the United States.


The 1840s comprised the end of the Tenpō era (1830–1844), the entirety of the Kōka era (1844–1848), and the beginning of the Kaei era (1848–1854). The decade saw the end of the reign of Emperor Ninko in 1846, who was succeeded by his son, Emperor Kōmei.

Southeastern Asia

The 1841–1845 Siamese-Vietnamese War in Cambodia was a war between Vietnam (then under the rule of the Nguyen dynasty) and Siam (Thailand) under the House of Chakkri. In the increasingly confrontational rivalry between Vietnam and Siam, the conflict was triggered by Vietnam's absorption of Cambodia and the demotion of the Khmer monarchs. Siam seized the opportunity to intervene as the tide of Khmer discontent rose against Vietnamese rule.


King Rama III ruled Siam during the 1840s under the Chakri dynasty in Bangkok.


Emperors Minh Mạng, Thiệu Trị and Tự Đức ruled Vietnam during the 1840s under the Nguyễn dynasty.

New Guinea

Australia and New Zealand

Southern Asia


The First Anglo-Afghan War had started in 1838, started by the British as a means of defending India (under British control at the time) from the Russian Empire's expansion into Central Asia.[citation needed] The British attempted to impose a puppet regime on Afghanistan under Shuja Shah, but the regime was short lived and proved unsustainable without British military support. By 1842, mobs were attacking the British on the streets of Kabul and the British garrison was forced to abandon the city due to constant civilian attacks. During the retreat from Kabul, the British army of approximately 4,500 troops (of which only 690 were European) and 12,000 camp followers was subjected to a series of attacks by Afghan warriors. All of the British soldiers were killed except for one and he and a few surviving Indian soldiers made it to the fort at Jalalabad shortly after. After the Battle of Kabul (1842), Britain placed Dost Mohammad Khan back into power (1842–1863) and withdrew from Afghanistan.


Map of India in 1848

Sikh Empire

The Sikh Empire was founded in 1799, ruled by Ranjit Singh. When Singh died in 1839, the Sikh Empire began to fall into disorder. There was a succession of short-lived rulers at the central Durbar (court), and increasing tension between the Khalsa (the Sikh Army) and the Durbar. In May 1841, the Dogra dynasty (a vassal of the Sikh Empire) invaded western Tibet, marking the beginning of the Sino-Sikh war. This war ended in a stalemate in September 1842, with the Treaty of Chushul.

The British East India Company began to build up its military strength on the borders of the Punjab. Eventually, the increasing tension goaded the Khalsa to invade British territory, under weak and possibly treacherous leaders. The hard-fought First Anglo-Sikh War (1845–1846) ended in defeat for the Khalsa. With the Treaty of Lahore, the Sikh Empire ceded Kashmir to the East India Company and surrendered the Koh-i-Noor diamond to Queen Victoria.

The Sikh empire was finally dissolved at the end of the Second Anglo-Sikh War in 1849 into separate princely states and the British province of Punjab. Eventually, a Lieutenant Governorship was formed in Lahore as a direct representative of the British Crown.

Sri Lanka

A memorial of Matale Rebellion, which began in Sri Lanka in 1848

Western Asia

Ottoman Empire

The decade was near the beginning of the Tanzimât Era of the Ottoman Empire. Sultan Abdülmecid I ruled during this period.


Emir Bashir Shihab II controlled the Mount Lebanon Emirate at the beginning of the 1840s. Bashir allied with Muhammad Ali of Egypt, but Muhammad Ali was driven out of the country. Bashir was deposed in 1840 when the Egyptians were driven out by an Ottoman-European alliance, which had the backing of Maronite forces. His successor, Emir Bashir III, ruled until 1842, after which the emirate was dissolved and split into a Druze sector and a Christian sector.


Persian Empire (Iran)

Revolutions of 1848

There was a wave of revolutions in Europe, collectively known as the Revolutions of 1848. It remains the most widespread revolutionary wave in European history, but within a year, reactionary forces had regained control, and the revolutions collapsed.

The revolutions were essentially bourgeois-democratic in nature with the aim of removing the old feudal structures and the creation of independent national states. The revolutionary wave began in France in February, and immediately spread to most of Europe and parts of Latin America. Over 50 countries were affected, but with no coordination or cooperation among the revolutionaries in different countries. Six factors were involved: widespread dissatisfaction with political leadership; demands for more participation in government and democracy; demands for freedom of press; the demands of the working classes; the upsurge of nationalism; and finally, the regrouping of the reactionary forces based on the royalty, the aristocracy, the army, and the peasants.

The uprisings were led by ad hoc coalitions of reformers, the middle classes and workers, which did not hold together for long. Tens of thousands of people were killed, and many more forced into exile. The only significant lasting reforms were the abolition of serfdom in Austria and Hungary, the end of absolute monarchy in Denmark, and the definitive end of the Capetian monarchy in France. The revolutions were most important in France, the Netherlands, Germany, Poland, Italy, and the Austrian Empire, but did not reach Russia, Sweden, Great Britain, and most of southern Europe (Spain, Serbia, Greece, Montenegro, Portugal, the Ottoman Empire).

Eastern Europe


Austrian Empire


Northern Europe



United Kingdom

April 10: "Monster Rally" of Chartists held on Kennington Common in London; the first photograph of a crowd depicts it.

Queen Victoria was on the throne 20 June 1837 until her death 22 January, 1901. The wedding of Queen Victoria and Prince Albert of Saxe-Coburg and Gotha took place in 1840.


The Great Famine of the 1840s caused the deaths of one million Irish people and over a million more emigrated to escape it. It is sometimes referred to, mostly outside Ireland, as the "Irish Potato Famine" because one-third of the population was then solely reliant on this cheap crop for a number of historical reasons. The proximate cause of famine was a potato disease commonly known as potato blight. A census taken in 1841 revealed a population of slightly over 8 million. A census immediately after the famine in 1851 counted 6,552,385, a drop of almost 1.5 million in 10 years.

The period of the potato blight in Ireland from 1845 to 1851 was full of political confrontation. A more radical Young Ireland group seceded from the Repeal movement and attempted an armed rebellion in the Young Irelander Rebellion of 1848, which was unsuccessful.

Western Europe



September 12: The Swiss Confederation reconstitutes itself as a federal republic.

The Netherlands


The frigate Belle-Poule brings back the remains of Napoleon to France.

Southern Europe


  • September 3, 1843 – Popular uprising in Athens, Greece, including citizens and military captains, to require from King Otto the issue of a liberal Constitution to the state, which has been governed since independence (1830) by various domestic and foreign business interests.

Italian Peninsula


This period saw the 1840 end of the First Carlist War, a civil war in Spain over the succession to the throne and the nature of the Spanish monarchy. This was the first full decade of the reign of Isabella II of Spain. Since she was only 10 years old in 1840, her true reign started in 1843, for which the first portion was referred to as Década moderada. The Affair of the Spanish Marriages (1846) was a series of intrigues between France, Spain, and the United Kingdom relating Isabella II's marriages, which was shortly followed by Second Carlist War (1847–1849).





South Africa



North America


In the prior decade, the desire for responsible government resulted in the abortive Rebellions of 1837–1838. The Durham Report subsequently recommended responsible government and the assimilation of French Canadians into English culture. The Act of Union 1840 merged the Canadas into a united Province of Canada and responsible government was established for all British North American provinces by 1849. The signing of the Oregon Treaty by Britain and the United States in 1846 ended the Oregon boundary dispute, extending the border westward along the 49th parallel. This paved the way for British colonies on Vancouver Island (1849) and in British Columbia (1858).

United States

The first U.S. postage stamps have portraits of Benjamin Franklin and George Washington. Though highly collectable, they are far from being the most valuable.
United States territorial growth from 1840 to 1850
Native Americans

Chief Joseph of the Nez Perce was predicted to have been born in the 1840s


The United States had five different Presidents during the decade. Only the 1880s would have as many. Martin Van Buren was president when the decade began, but was defeated by William Henry Harrison in the U.S. presidential election of 1840. Harrison's service was the shortest in history, starting with his inauguration on March 4, 1841, and ending when he died on April 4, 1841.

Harrison's vice president, John Tyler, replaced him as President (the first such Presidential succession in U.S. history), and served out the rest of his term. Tyler spent much of his term in conflict with the Whig party. He ended his term having made an alliance with the Democrats, endorsing James K. Polk and signing the resolution to annex Texas into the United States.

In the Presidential election of 1844, James K. Polk defeated Henry Clay. During his presidency, Polk oversaw the U.S. victory in the Mexican–American War and subsequent annexation of what is now the southwest United States. He also negotiated a split of the Oregon Territory with Great Britain.

In the U.S. presidential election of 1848, Whig Zachary Taylor of Louisiana defeated Democrat Lewis Cass of Michigan. Taylor's term in office was cut short by his death in 1850.


In the first part of the 1840s, the modern state of California was part of a larger province of Mexico, called "Alta California". The region included all of the modern American states of California, Nevada and Utah, and parts of Arizona, Wyoming, Colorado and New Mexico.

The United States, embarked on the Conquest of California in an early military campaign of the Mexican–American War in Alta California. The California Campaign was marked by a series of small battles throughout 1846 and early 1847. The Treaty of Cahuenga was signed on January 13, 1847, and essentially terminated hostilities in Alta California. Shortly thereafter, John C. Frémont was appointed Governor of the new California Territory, and Yerba Buena, California, was renamed San Francisco.

The Treaty of Guadalupe Hidalgo, signed in February 1848, marked the end of the Mexican–American War. By the terms of the treaty, Mexico formally ceded Alta California along with its other northern territories east through Texas, receiving $15,000,000 in exchange. This largely unsettled territory constituted nearly half of its claimed territory with about 1% of its then population of about 4,500,000.

The discovery of gold in Northern California (and subsequent discourse about that discovery in 1848) led to the California Gold Rush. In October 1848, the SS California left New York Harbor, rounded Cape Horn at the tip of South America, and arrived in San Francisco after the 4-month-21-day journey. Thereafter, regular steamboat service continued from the west to the east coast of the United States. During 1848, only an estimated 6,000 to 6,500 people traveled to California to seek gold that year. By the beginning of 1849, word of the Gold Rush had spread around the world, and an overwhelming number of gold-seekers and merchants began to arrive from virtually every continent. In 1849, an estimated 90,000 people arrived in California in 1849—of which 50,000 to 60,000 were from the United States. In 1850, California joined the union as the 31st state.


The Republic of Texas had declared independence in 1836, as part of breaking away from Mexico in the Texas Revolution. The following year, an ambassador from Texas approached the United States about the possibility of becoming an American state. Fearing a war with Mexico, which did not recognize Texas independence, the United States declined the offer.

In 1844, James K. Polk was elected the United States president after promising to annex Texas. Before he assumed office, the outgoing president, John Tyler, entered negotiations with Texas. On February 26, 1845, six days before Polk took office, the U.S. Congress approved the annexation. The Texas legislature approved annexation in July 1845 and constructed a state constitution. In October, Texas residents approved the annexation and the new constitution, and Texas was officially inducted into the United States on December 29, 1845, as the 28th U.S. state. Mexico still considered Texas to be a renegade Mexican state, and never considered land south of the Nueces River to be part of Texas. This border dispute between the newly expanded United States and Mexico triggered the Mexican–American War.

When the war concluded, Mexico relinquished its claim on Texas, as well as other regions in what is now the southwestern United States. Texas' annexation as a state that tolerated slavery had caused tension in the United States among slave states and those that did not allow slavery. The tension was partially defused with the Compromise of 1850, in which Texas ceded some of its territory to the federal government to become non-slave-owning areas but gained El Paso.

Mexican–American War

American territorial expansion to the Pacific coast was a major goal of U.S. President James K. Polk. In 1845, the United States of America annexed Texas, which had won independence from Centralist Republic of Mexico in the Texas Revolution of 1836. Mexico did not accept the annexation, while also continuing to claim the Nueces River as its border with Texas, and also still considering Texas to be a province of Mexico. In 1845, newly elected U.S. President James K. Polk sent troops to the disputed area, and a diplomatic mission to Mexico. After Mexican forces attacked American forces, the U.S. declared the Mexican–American War (1846–1848).

Combat operations lasted a year and a half, from the spring of 1846 to the fall of 1847. U.S. forces quickly occupied the capital town of Santa Fe de Nuevo México along the upper Rio Grande and began the Conquest of California in Mexico's Alta California Department. They then invaded to the south into parts of central Mexico (modern-day northeastern Mexico and northwest Mexico). Meanwhile, the Pacific Squadron of the United States Navy conducted a blockade and took control of several garrisons on the Pacific coast farther south in lower Baja California Territory. The U.S. Army eventually captured the capital Mexico City, having marched west from the port of Veracruz, where the Americans staged their first amphibious landing on the Gulf of Mexico coast.

The 1848 Treaty of Guadalupe Hidalgo, forced onto the remnant Mexican government, ended the war and specified its major consequence, the Mexican Cession of the northern territories of Alta California and Santa Fe de Nuevo México to the United States. The U.S. agreed to pay $15 million compensation for the physical damage of the war. In addition, the United States assumed $3.25 million of debt already owed earlier by the Mexican government to U.S. citizens. Mexico acknowledged the loss of their province, later the Republic of Texas (and now the State of Texas), and thereafter cited and acknowledged the Rio Grande as its future northern national border with the United States. Including Texas, Mexico ceded an area of approximately 2,500,000 square kilometres (970,000 sq mi) – by its terms, around 55% of its former national territory.


The 1840s for Mexico were the end of the centralist government and the waning years the "Age of Santa Anna". In 1834, President Antonio López de Santa Anna dissolved Congress, forming a new government. That government instituted the new Centralist Republic of Mexico by approving a new centralist constitution ("Siete Leyes"), From its formation in 1835 until its dissolution in 1846, the Centralist Republic was governed by eleven presidents (none of which finished their term). It called for the state militias to disarm, but many states resisted, including Mexican Texas, which won its independence in the Texas Revolution of 1836.

The Republic of the Rio Grande declared its independence from Mexico in January 1840. However, the border with Texas was never determined (whether the Nueces River or the Rio Grande). The new Republic fought a brief and unsuccessful war for independence, returning to Mexico late in the year.

In 1841, Generals Santa Anna and Paredes led a rebellion against President Bustamante, resulting in Santa Anna becoming president of the centralist government for a fifth time . Local officials in Yucatán declared independence in 1841, opposing strong autocratic rule and demanding the restoration of the Constitution of 1824, thus establishing the second Republic of Yucatán.

In 1842, the region of Soconusco was annexed by Mexico as part of the state of Chiapas, following the dissolution of the Federal Republic of Central America.

In 1846, President Paredes and the Congress of Mexico declared war at the beginning of the Mexican–American War. Paredes' presidential successor was deposed in a coup, replaced by José Mariano Salas. Salas issued a new decree that restored the Constitution of 1824, ending the Centralist Republic and beginning the Second Federal Republic of Mexico. After the conclusion of the Mexican–American War, José Joaquín de Herrera became the second president of Mexico to finish his term (Mexico's first president completed his in 1829). It was during this time that Yucatán reunited with Mexico. A decisive factor for the reunion was the Caste War of Yucatán (a revolt by the indigenous Maya population) for which Yucatán initially sought help from Spain, the United Kingdom, and the United States, but ultimately reunited with Mexico for help.

Herrera peacefully turned over the presidency to the winner of the Federal Elections of 1850, General Mariano Arista. Despite being exiled from Mexico in 1848, Santa Anna would return to the presidency one last time during the 1850s.

El Salvador



Dominican Republic



South America








Science and technology


Mechanical engineering


The 1840s saw the rise of the Daguerreotype. Introduced in 1839, the Daguerreotype was the first publicly announced photographic process and came into widespread use in the 1840s. Numerous events in the 1840s were captured by photography for the first time with the use of the Daguerreotype. A number of daguerreotypes were taken of the occupation of Saltillo during the Mexican–American War, in 1847 by an unknown photographer. These photographs stand as the first ever photos of warfare in history.






  • 1840Louis Agassiz publishes his Etudes sur les glaciers ("Study on Glaciers", 2 volumes), the first major scientific work to propose that the Earth has seen an ice age.













Widespread interest to invest in rail technology led to a speculative frenzy in Britain, known there as Railway Mania. It reached its zenith in 1846, when no fewer than 272 Acts of Parliament were passed, setting up new railway companies, and the proposed routes totalled 9,500 miles (15,300 km) of new railway. Around a third of the railways authorised were never built – the company either collapsed due to poor financial planning, was bought out by a larger competitor before it could build its line, or turned out to be a fraudulent enterprise to channel investors' money into another business.

Steam power

January 13: Steamship Lexington sinks.

Other inventions


Civil rights

Women's rights

Popular culture






Queen Victoria and the Prince Consort at home, 1841. Her dress shows the fashionable silhouette, with its pointed waist, sloping shoulder, and bell-shaped skirt.

Fashion in European and European-influenced clothing is characterized by a narrow, natural shoulder line following the exaggerated puffed sleeves of the later 1820s fashion and 1830s fashion. The narrower shoulder was accompanied by a lower waistline for both men and women.


Religion and philosophy

Disasters, natural events, and notable mishaps


The third cholera pandemic happened during the 1840s, which researchers at UCLA believe may have started as early as 1837 and lasted until 1863. This pandemic was considered to have the highest fatalities of the 19th-century epidemics. It originated in India (in Lower Bengal), spreading along many shipping routes in 1846. Over 15,000 people died of cholera in Mecca in 1846. In Russia, between 1847 and 1851, more than one million people died in the country's epidemic.

A two-year outbreak began in England and Wales in 1848, and claimed 52,000 lives. In London, it was the worst outbreak in the city's history, claiming 14,137 lives, over twice as many as the 1832 outbreak. Cholera hit Ireland in 1849 and killed many of the Irish Famine survivors, already weakened by starvation and fever. In 1849, cholera claimed 5,308 lives in the major port city of Liverpool, England, an embarkation point for immigrants to North America, and 1,834 in Hull, England. In 1849, a second major outbreak occurred in Paris.

Cholera, believed spread from Irish immigrant ship(s) from England to the United States, spread throughout the Mississippi river system, killing over 4,500 in St. Louis and over 3,000 in New Orleans. Thousands died in New York, a major destination for Irish immigrants. The outbreak that struck Nashville in 1849–1850 took the life of former U.S. President James K. Polk. During the California Gold Rush, cholera was transmitted along the California, Mormon and Oregon Trails as 6,000 to 12,000 are believed to have died on their way to Utah and Oregon in the cholera years of 1849–1855. It is believed cholera claimed more than 150,000 victims in the United States during the two pandemics between 1832 and 1849, and also claimed 200,000 victims in Mexico.






  • October 1, 1846Christ College, Tasmania, opens with the hope that it would develop along the lines of an Oxbridge college and provide the basis for university education in Tasmania. By the 21st century it will be the oldest tertiary institution in Australia.



North America


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