In August 1903 Dyer was promoted to major, and served with the Landi Kotal Expedition (1908). He commanded the 25th Punjabis in India and Hong Kong and was promoted to lieutenant-colonel in 1910. During the First World War (1914–18), he commanded the Seistan Force, for which he was mentioned in dispatches and made a Companion of the Order of the Bath (CB). He was promoted colonel in 1915, and was promoted to temporary brigadier general in 1916. In 1919, about a month after the Jallianwala Bagh massacre, Dyer served in the Third Anglo-Afghan War. His brigade relieved the garrison of Thal, for which he was again mentioned in dispatches. For a few months in 1919 he was posted to the 5th Brigade at Jamrud.