Palmes served between 1914 and 1918 in World War I with the 10th Royal Hussars and was woundedtwice. He was awarded the Military Cross "for conspicuous gallantry and devotion to duty. He assumed command of the regiment under very difficult circumstances and organised the defence of his position. He showed great courage and ability under very heavy fire, and on relief volunteered to hold his posts for a further twenty-four hours, which he did with two of his squadrons".