Comparative atlas
Compare eras and explore the sources for each record.
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The overview groups by start date; the left edge also includes periods that started earlier. Turn it off to see durations. Totals count unique records; layers can share records.
c. 1500 CE–c. 1867 CE
For more than three centuries, commercial networks and states forcibly transported millions of Africans to the Americas. The trade was a system of violence, dispossession, and resistance that linked Atlantic economies; its chronologies and forms changed by empire, port, and community, and legal abolitions did not immediately end either slavery or clandestine trafficking.
Period or process · World
c. 1760 CE–c. 1913 CE
Mechanization that began in Great Britain spread unevenly through coal, steam, factories, railways, steel, electricity, and new communications. It generated wealth and productive capacity, but also precarious work, pollution, and unequal relationships among industrial centers, colonies, and export economies; it was neither uniform nor inevitable.
Period or process · World
c. 1775 CE–c. 1825 CE
Wars and uprisings in North America, France, the Caribbean, and Spanish America challenged monarchies, empires, and colonial orders. Ideas, people, and resources circulated across the Atlantic, but their political projects, social bases, and outcomes differed; many colonial hierarchies and forms of exclusion persisted after independence.
Period or process · World
c. 1791 CE–c. 1804 CE
The rebellion of enslaved people, free people of color, and other inhabitants of Saint-Domingue became a revolution that defeated the French colonial regime and culminated in Haiti’s independence in 1804. Its impact crossed the Atlantic world and challenged slavery, though the new republic faced isolation, imposed debt, and internal conflict.
Period or process · World
1798 CE–1801 CE
The United Irishmen organized a republican, cross-confessional rebellion followed by extreme repression and sectarian violence. The Acts of Union abolished the Irish Parliament and created the United Kingdom of Great Britain and Ireland; Ireland was both subordinated within the union and deeply implicated in empire
Period or process · British Empire
1800 CE
Alessandro Volta’s pile supplied continuous electric current, making electricity a reproducible energy source in the laboratory and later in practical technologies.
Historical milestone · Energy
c. 1800 CE–c. 1900 CE
Marshallese navigators built stick-and-shell charts to model swells, refraction, and relationships among atolls. They were teaching and memory aids interpreted by specialists before a voyage, not scale maps or objects normally consulted at sea.
Period or process · Oceans, navigation & cartography
1819 CE–1901 CE
Victoria reigned from 1837 to 1901 during the empire’s major territorial, commercial and military expansion and received the title Empress of India in 1876. Monarchy functioned as a symbol of imperial unity and racial and social hierarchy, although ministers, Parliament, companies and colonial authorities made many decisions. Her profile explains imperial political culture without attributing every war, annexation or policy to her personally
Person · British Empire
1824 CE–1832 CE
British pastoral expansion in Van Diemen’s Land intensified a frontier war among settlers, colonial forces and Tasmanian Aboriginal peoples. In 1830 Governor George Arthur mobilized the “Black Line,” a mass operation intended to drive together and capture survivors; it failed militarily but accompanied a policy of removal and confinement. Tongerlongeter, Mannalargenna and other Aboriginal figures represent resistance, negotiation and survival against violence that cannot be narrated as the mere extension of settlement
Period or process · British Empire
1828 CE–1858 CE
Lakshmibai ruled Jhansi and contested the East India Company’s annexation of her state under the doctrine of lapse. During the 1857–1858 rebellion she organized and led forces against the British, left Jhansi after its siege and died fighting near Gwalior. Indian and British memories made her an emblematic figure, but her historical importance also lies in a concrete defense of dynastic and territorial sovereignty
Person · British Empire
1831 CE
Michael Faraday’s experiments showed how relative motion between magnets and conductors generates current. The principle made generators and electric grids possible.
Historical milestone · Energy
1840 CE
Crown representatives and more than five hundred Māori rangatira signed non-equivalent Māori and English texts: especially `kawanatanga` and `tino rangatiratanga` conveyed different understandings of government and authority. The treaty remains a constitutional foundation and the basis of claims over breaches
Institutional milestone · British Empire
1844 CE
A line between Washington and Baltimore carried Morse’s first public telegraph message. Electric signaling turned distant messaging into near-instant infrastructure.
Historical milestone · Information & communication
c. 1847 CE
Matthew Fontaine Maury systematized observations from many logbooks to produce wind-and-current charts and sailing directions. The method shortened routes and turned data contributed by many mariners into operational knowledge, although institutional authorship should not hide that collective work.
Historical milestone · Oceans, navigation & cartography
c. 1848 CE–c. 1849 CE
Uprisings in numerous European states demanded, in differing combinations, constitutions, representation, social reform, and national self-determination. Most were defeated or limited in the short term, but the wave left political changes and exile networks; it was not a single revolution and did not affect all of Europe alike.
Period or process · World
c. 1850 CE–c. 1871 CE
By the mid-nineteenth century, general staffs and civil administrations increasingly coordinated reserves, trains, maps, supplies, and telegraphic communications to concentrate forces. The Prussian case shows both the possibilities of railway plans and their limits: rapid transport alone did not solve loading, storage, supply, political decisions, or an opponent’s response.
Period or process · War & military technology
1858 CE
The Government of India Act transferred the Company’s territories and functions to the Crown and created a secretary of state for India. Victoria’s proclamation promised religious toleration and respect for princes and property while consolidating a more centralized and racialized Raj
Historical milestone · British Empire
1859 CE
Edwin Drake’s drilled well in Pennsylvania triggered the modern oil boom. It was not petroleum’s first use, but a turning point for commercial extraction by drilling.
Historical milestone · Energy
1866 CE
After several failed attempts, the 1866 cable operationally connected Ireland and Newfoundland and reduced messages that had traveled for days by ship to minutes. It was costly, fragile infrastructure initially oriented toward states, news, and business, not universal or instantaneous communication for everyone.
Historical milestone · Information & communication
1867 CE
The British North America Act federated Ontario, Quebec, Nova Scotia, and New Brunswick under the Crown. The new dominion gained broad settler self-government and soon extended authority west and north without general consent from First Nations, Inuit, and Métis peoples
Historical milestone · British Empire
c. 1868 CE–c. 1912 CE
The fall of the Tokugawa shogunate in 1868 began a reorganization of power in the emperor’s name and programs of state, military, educational, and industrial reform. The transformation incorporated and adapted international models amid intense internal conflict; it was not a simple “Westernization” or a uniform social experience.
Period or process · World
1869 CE
The opening of the Suez Canal shortened the sea route between the Mediterranean and the Indian Ocean and reordered logistics, trade, and imperial strategy. Its benefits and costs were distributed unevenly, and the canal depended on transnational labor, finance, and political control; it did not wholly replace existing routes.
Historical milestone · World
c. 1870 CE–c. 1913 CE
Between the 1870s and 1913, a growing number of states linked their currencies to gold and international flows of capital, trade, and migration expanded. Integration was partial and unequal: many colonial or dependent territories did not set their own rules, and crises and border controls continued to shape movement.
Period or process · World
1871 CE–1876 CE
Between 1871 and 1876 the Canadian Crown concluded the first six Numbered Treaties with multiple First Nations while Parliament enacted the Indian Act. Crown texts recorded territorial surrenders in exchange for reserves, payments and promises; many Indigenous interpretations instead hold that the agreements concerned sharing the land and maintaining an enduring relationship with the Crown. The Indian Act consolidated coercive federal authority over community status, lands and government, making imperial continuity within the Canadian state visible
Period or process · British Empire
c. 1871 CE–c. 1914 CE
After unification in 1871, the reputation of the Prussian-German General Staff encouraged detailed planning for mobilization, deployment, and operations and influenced other military establishments. That reputation does not equal infallibility or total political control: plans depended on diplomatic assumptions, railways, reserves, incomplete information, and decisions by governments and commanders.
Period or process · War & military technology
1872 CE–1876 CE
The HMS Challenger expedition circumnavigated the globe measuring depth, temperature, salinity, currents, and sediments while collecting organisms. Its stations were scattered points rather than a complete map, but they established a quantitative, multidisciplinary foundation for modern oceanography and bathymetry.
Period or process · Oceans, navigation & cartography
1873 CE–1878 CE
The Meiji government introduced conscription in 1873 and created a General Staff in 1878 within a reorganization combining models, advisers, and resources from diverse origins. These institutions displaced the samurai military monopoly and strengthened state capacity, without being a mere European copy or a socially neutral transition: the burdens of service, taxation, and centralization prompted contestation and changed unevenly.
Period or process · War & military technology
1874 CE–1965 CE
Churchill was a soldier, colonial minister and prime minister during the Second World War and again from 1951 to 1955. He openly defended empire, opposed Indian self-government and participated in wartime decisions affecting imperial populations, including the Bengal crisis. His role in defeating Nazism does not erase his racial ideas or imperial policies; both dimensions belong together and require historically precise causal claims
Person · British Empire
c. 1875 CE–c. 1902 CE
The major hunger crises of 1875–1878 and 1896–1902 coincided with extensive droughts linked to climate variability, especially in tropical and subtropical regions. Deaths and suffering cannot be attributed to climate alone: colonial policies, markets, war, food access, and local responses decisively shaped their effects.
Period or process · World
1876 CE
Bell received a patent and demonstrated an apparatus capable of transmitting voice; its development was collective and contested. The telephone enabled real-time conversation over wired networks.
Historical milestone · Information & communication
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