This medal was awarded for meritorious or distinguished service by officers of the armed forces during wartime, typically in actual combat, serving under fire, and usually awarded to those above the rank of captain. Until 1943, the recipient must have been mentioned in despatches by the commander-in-chief of the Army, or admiral of the Navy.
Between 1914 and 1916, the DSO could also be awarded to staff officers when they were not under fire or in contact with the enemy, but by 1917, it was once more restricted to those who had served in the presence of the enemy. On 23 August 1916, a warrant allowed a bar to be awarded as a way of formally recognising further acts of merit.
