Garland rose to become Superintendent of Laboratories at the Cairo Citadel, Egypt by 1913 and received a grant from the Chemical Society, of which he was a fellow, to conduct research into ancient Egyptian alloys.

Awarded the Military Cross and appointed an Officer of the Order of the British Empire, Garland became director of the Arab Bureau after the war and was involved in the post-war negotiations for the future of Arabia.

[2][3] Garland was later transferred to Khartoum, Sudan and by the outbreak of the First World War was Superintendent of Laboratories at the Cairo Citadel, Egypt, where he had received a grant from the Chemical Society to research ancient Egyptian alloys.

[3][11] There he applied his practical knowledge of explosives to developing mines, teaching T. E. Lawrence and the Arab rebels to use them during their guerilla campaign and contributing to the British capture of Damascus and the eventual downfall of the Ottoman Empire.

[14] Garland saw to it that a defensive trench was dug by the townsfolk, barbed wire entanglements were established, machine gun positions were correctly sited and the towns' 300-year-old coral walls were strengthened.

[11] With the supporting gunfire and searchlights of five Royal Navy vessels he held off advancing Ottoman forces in a relatively bloodless victory that ensured the continuance of the Arab Revolt.

[11][13] The searchlights were thought by one of Garland's men to have been key to winning the battle, being used to discourage an Ottoman attack by highlighting the coverless plain that had to be crossed prior to reaching the town.

[4] Garland's main task was to resolve the post-war state of the Arabian Peninsula which the war had left in the hands of a number of competing Arab tribes and to tackle the delicate matter of the ending of lavish subsidies from the British treasury to Hussein bin Ali, Sharif of Mecca.