Starting on 13 May 1941, the Germans had aircraft based at Mosul and Erbil to aid the Iraqi's in their fight against the British. Three German He-111 bombers raided Habbaniyah on 16 May and were able to do considerable damage. The German aircraft lacked the necessary support, however, so there were only one fighter and one bomber still operational by 28 May.
The Iraqi anti-British group were upset at the lack of support by the Germans and Italians. The Iraqis wanted arms and gold. Apparently, any Arab revolt against the British needed to have gold, presumably to buy support. The Germans saw the Iraqi revolt as more of a political event, rather than a real uprising of the Iraqi people against the British. The latter might have actually received substantive support. This is based on the account in Vol.II of the Australian Official History.