| Unit Name: | 45th Brigade 45th Infantry Brigade |
| Dates: | 1914–1918 1939–1946 |
| Country: |  United Kingdom |
| Branch: | Kitchener's Army |
| Type: | Infantry |
| Size: | Brigade |
| Command Structure: | 15th (Scottish) Infantry Division |
| Identification Symbol: | Divisional Insignia Scottish Red Lion Rampant, inside a yellow circle |
| Battles: | First World War |
The 45th Infantry Brigade was an infantry brigade of the British Army that saw active service in both the First and the Second World Wars with 15th (Scottish) Infantry Division.
The brigade was raised, as 45th Brigade, in 1914 as part of Kitchener's New Armies shortly after the outbreak of the First World War. With the 15th (Scottish) Division, the brigade saw active service on the Western Front in Belgium and France.
The brigade command the following units:[1]
The 7th (Service) Battalion, Royal Scots Fusiliers was an original member of the brigade. It merged with the 6th (Service) Battalion in May 1916 to form the 6th/7th Battalion.
The brigade was reformed just before the Second World War, as the 45th Infantry Brigade. The brigade was a 2nd Line Territorial Army formation and was part of the 15th (Scottish) Infantry Division, which was the duplicate of the 52nd (Lowland) Infantry Division and served in the Second World War. The brigade was formed as a duplicate of the 156th Infantry Brigade. It remained in the United Kingdom throughout the war and, in early January 1943, left the 15th Division and was replaced by 6th Guards Tank Brigade. The Brigade was then assigned to the 80th Infantry (Reserve) Division for training purposes. Once the 80th was disbanded, the brigade was assigned to the 38th Infantry (Reserve) Division whose control it remained under for the duration of the war.
During the war, the brigade contained the following units: