A September 1917 entry in "The London Gazette" noted that Philipps relinquished his Army commission earlier in the year, with no explanation provided. This decision was due to injury: his entry in the 1951 "Who's Who" describes being 'invalided', indicating wounds had rendered him unfit for further duty, and is further confirmed by a letter sent by Philipps to Reginald Wingate which suggests he had returned to Britain in March. Philipps quickly recovered and restored his commission: he was employed at the War Office in London with the Intelligence Staff, June–August 1917; then was similarly employed at the Admiralty, August–October 1917. By November 1917 he was in Abyssinia on a mission to investigate the extent of the slave trade. The next month he was reportedly present at the Capture of Jerusalem. In 1918 he began a posting at the Arab Bureau (a section of the Cairo Intelligence Department), operating as an Intelligence Officer at their headquarters in Cairo. This was a role generally based in Cairo, with spells in Palestine and Syria, working alongside Lawrence of Arabia in the final campaigns of the Arab Revolt. His work with the Bureau was interrupted by his taking part in a military expedition against the Turkana people (April–June 1918), who lived on the fringes of British East Africa and were notorious for raiding cattle.