1st Division (United Kingdom) may refer to:

• 1st (United Kingdom) Division: active division of the British Army, which was originally formed in 1809. Previously known as the 1st Division, No.1 Division, 1st Infantry Division, and 1st Armoured Division (1978–2014).
• 1st Armoured Division: known as the Mobile Division between 1937 and 1939. Disbanded in 1945. In 1946, a new formation was created when the 6th Armoured Division was renamed. That formation was disbanded in 1947.
• 1st Cavalry Division (United Kingdom): Previously known as the Cavalry Division and fought during the Napoleonic Wars, the Crimean War, the Second Boer War. During the Second World War, a new formation was raised, and subsequently became the 10th Armoured Division.

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