In mid-1942, Deac and his Australian Pilot, Sgt Gordon Nettleship, were sent on a troop ship via North America to Takoradi in West Africa, formerly the Gold Coast Their Beaufighter aircraft had been shipped in crates and assembled in Takoradi before they flew the ‘Takoradi Run’ north over Nigeria, the Sahara Desert, Sudan and Egypt. 

Upon arrival in Egypt, they were assigned to 252 Squadron, based at Edu, west of Alexandria. 252 Squadron specialsed in anti-shipping attacks against the Italian and German Navies and forces in North Africa and the region around Malta. The main task was to disrupt the enemy’s supply chain and soften up the armies before the Allied push at El Alamein. From 252 Squadron, Gordon and Deac were transferred to 227 and 272 squadrons based in the recently relieved Malta. Ultra-Low-Level Anti-Shipping strikes continued including around Tunis, Algeria, Libya and Sicily until March 1943 when they were posted back to England.

The pressure on North Africa had subsided and the focus moved to Europe. The return journey started in Suez and returned to England via Durban and Rio de Janeiro to avoid the North Atlantic U-Boat attacks. Flying recommenced in July, initially in Beaufighters of Coastal Command either conducting air-sea rescue searches across the North Sea or training other crews.

In January 1944, Deac joined No.9 Operational Training Unit at Crosby on Eden, converting to the Mosquito bomber aircraft. In April 1944 he joined 571 Squadron, part of 8 Group Bomber Command. Part of the Pathfinder Force based at RAF Oakington.   During this time Deac was involved in the development and air testing of the new Navigational aids being introduced, including Gee, H2S and Oboe. Mosquito bombing raids were conducted over German cities including the Ruhr, Berlin, Hanover, Bremen, and Frankfurt. In October 1944 Deac had completed 100 Operational Missions and was awarded his first DFC. This was rapidly followed by a second, after he navigated Mosquitos to lay mines at ultra-low level in the Kiel Canal.