On 5 April 1941, Jackson fired several bursts at a Ju 87 before his guns jammed; he then made two dummy attacks and forced the German plane to crash land in a wadi, thus claiming his fourth victory. After converting to P-40 Tomahawks, No. 3 Squadron took part in the Syria–Lebanon campaign. Jackson became an ace on 25 June, when he destroyed a Potez 630 light bomber (possibly a misidentified LeO 451) of the Vichy French air force. He claimed a Dewoitine D.520 fighter on 10 July. The next day Jackson shared in the destruction of another D.520 with Bobby Gibbes; the pair tossed a coin to take full credit for it; Gibbes won to claim his first "kill".