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| British Army lists |
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| French Revolutionary and Napoleonic Wars |
| Victorian era |
| First World War |
| Second World War |
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This page is a list of British army-level formations existing during the First World War.
The British Armed Forces are the military forces responsible for the defence of the United Kingdom, its Overseas Territories and the Crown Dependencies. They also promote the UK's wider interests, support international peacekeeping efforts and provide humanitarian aid.
The British Expeditionary Force (BEF) was the six divisions the British Army sent to the Western Front during the First World War. Planning for a British Expeditionary Force began with the 1906–1912 Haldane Reforms of the British Army carried out by the Secretary of State for War Richard Haldane following the Second Boer War (1899–1902).
The American Expeditionary Forces (AEF) was a formation of the United States Armed Forces on the Western Front during World War I, composed mostly of units from the U.S. Army. The AEF was established on July 5, 1917, in France under the command of then-Major General John J. Pershing. It fought alongside French Army, British Army, Canadian Army, British Indian Army, New Zealand Army and Australian Army units against the Imperial German Army. A small number of AEF troops also fought alongside Italian Army units in 1918 against the Austro-Hungarian Army. The AEF helped the French Army on the Western Front during the Aisne Offensive in the summer of 1918, and fought its major actions in the Battle of Saint-Mihiel and the Meuse-Argonne Offensive in the latter part of 1918.
The First Army was a formation of the British Army that existed during the First and Second World Wars. The First Army included Indian and Portuguese forces during the First World War and American and French units during the Second World War.
The British Second Army was a field army active during the First and Second World Wars. During the First World War the army was active on the Western Front throughout most of the war and later active in Italy. During the Second World War the army was the main British contribution to the Normandy landings on 6 June 1944 and advance across Europe.
The Canadian Corps was a World War I corps formed from the Canadian Expeditionary Force in September 1915 after the arrival of the 2nd Canadian Division in France. The corps was expanded by the addition of the 3rd Canadian Division in December 1915 and the 4th Canadian Division in August 1916. The organization of a 5th Canadian Division began in February 1917 but it was still not fully formed when it was broken up in February 1918 and its men used to reinforce the other four divisions.
The Territorial Force was a part-time volunteer component of the British Army, created in 1908 to augment British land forces without resorting to conscription. The new organisation consolidated the 19th-century Volunteer Force and yeomanry into a unified auxiliary, commanded by the War Office and administered by local county territorial associations. The Territorial Force was designed to reinforce the regular army in expeditionary operations abroad, but because of political opposition it was assigned to home defence. Members were liable for service anywhere in the UK and could not be compelled to serve overseas. In the first two months of the First World War, territorials volunteered for foreign service in significant numbers, allowing territorial units to be deployed abroad. They saw their first action on the Western Front during the initial German offensive of 1914, and the force filled the gap between the near destruction of the regular army that year and the arrival of the New Army in 1915. Territorial units were deployed to Gallipoli in 1915 and, following the failure of that campaign, provided the bulk of the British contribution to allied forces in the Sinai and Palestine Campaign. By the war's end, the Territorial Force had fielded twenty-three infantry divisions and two mounted divisions on foreign soil. It was demobilised after the war and reconstituted in 1921 as the Territorial Army.
An army group is a military organization consisting of several field armies, which is self-sufficient for indefinite periods. It is usually responsible for a particular geographic area. An army group is the largest field organization handled by a single commander – usually a full general or field marshal – and it generally includes between 400,000 and 1,000,000 soldiers.
The New Zealand Expeditionary Force (NZEF) was the title of the military forces sent from New Zealand to fight alongside other British Empire and Dominion troops during World War I (1914–1918) and World War II (1939–1945). Ultimately, the NZEF of World War I became known as the First New Zealand Expeditionary Force. The NZEF of World War II was known as the Second New Zealand Expeditionary Force (2NZEF).
The Canadian Expeditionary Force (CEF) was the expeditionary field force of Canada during the First World War. It was formed on 15 August 1914 following Britain’s declaration of war on the German Empire, with an initial strength of one infantry division. The division subsequently fought at Ypres on the Western Front, with a newly raised second division reinforcing the committed units to form the Canadian Corps. The CEF and corps was eventually expanded to four infantry divisions, which were all committed to the fighting in France and Belgium along the Western Front. A fifth division was partially raised in 1917, but was broken up in 1918 and used as reinforcements following heavy casualties.
The Hundred Days Offensive was a series of massive Allied offensives that ended the First World War. Beginning with the Battle of Amiens on the Western Front, the Allies pushed the Imperial German Army back, undoing its gains from the German spring offensive.
GHQ Central Force was a home command of the British Army during the First World War.
The Third Battle of the Aisne was part of the German spring offensive during World War I that focused on capturing the Chemin des Dames Ridge before the American Expeditionary Forces arrived completely in France. It was one of a series of offensives, known as the Kaiserschlacht, launched by the Germans in the spring and summer of 1918.
The 32nd Infantry Division was a French Army formation during World War I and World War II.
Battle of Northern Burma and Western Yunnan was the name of the Chinese campaign with their allies in the 1943–45 Burma Campaign. The campaign ended in an Allied victory.
The Chinese Expeditionary Force was an expeditionary unit of China's National Revolutionary Army that was dispatched to Burma and India in support of the Allied efforts against the Imperial Japanese Army during the Japanese invasion and occupation of Burma in the South-East Asian theatre of the Second World War.
Expeditionary warfare is a military invasion of a foreign territory, especially away from established bases. Expeditionary forces were in part the antecedent of the modern concept of rapid deployment forces. Traditionally, expeditionary forces were essentially self-sustaining with an organic logistics capability and with a full array of supporting arms.
The Tenth Army was a Field army of the French Army during World War I and World War II.
The Allied leaders of World War I were the political and military figures that fought for or supported the Allied Powers during World War I.
The Haldane Reforms were a series of far-ranging reforms of the British Army made from 1906 to 1912, and named after the Secretary of State for War, Richard Burdon Haldane. They were the first major reforms since the "Childers Reforms" of the early 1880s, and were made in the light of lessons newly learned in the Second Boer War.