Barr was posted to North Africa on 28 September 1941, to fly with No. 3 Squadron under the command of Squadron Leader Peter Jeffrey. He converted to P-40 Tomahawk fighters at an RAF operational training unit in Khartoum. There he also received his "goolie chit", a piece of paper to be shown to local tribesmen in the event he was shot down, reading in Arabic: "don't kill the bearer, feed him and protect him, take him to the English and you will be rewarded. Peace be upon you." Returning to North Africa, Barr achieved his first aerial victory, over a Messerschmitt Bf 110, on 12 December. He followed this up with a Junkers Ju 88 and a Messerschmitt Bf 109 the next day. The squadron then re-equipped with P-40 Kittyhawks; Barr was flying the new model when he became an ace on New Year's Day 1942, shooting down two Junkers Ju 87 "Stukas". On 8 March, he led a flight of six Kittyhawks to intercept a raid on Tobruk by twelve Ju 87s escorted by ten Macchi C. 202s and two Bf 109s. The Australians destroyed six Macchis and three Ju 87s without loss, Barr personally accounting for one of the Macchis.