Caldwell was 24 years old, and a Sergeant in the 12th (Ayr and Lanark Yeomanry) Battalion, the Royal Scots Fusiliers during the First World War when the following deed took place for which he was awarded the VC.
For most conspicuous bravery and initiative in attack near Audenarde on 31 October 1918 near Audenarde, Belgium, when in command of a Lewis gun section engaged in clearing a farmhouse.