Early results in the Mediterranean Theater of Operations were mixed. Some P-38 pilots scored multiple kills to become aces, while many others were shot down due to inexperience or tactical strictures. Overall, the P-38 suffered its highest losses in the Mediterranean Theater. The primary function of the P-38 in North Africa was to escort bombers, but the fighters also targeted transport aircraft, and later in the campaign they were sometimes tasked with ground attack missions. When tied to bomber escort duties, the P-38 squadrons were vulnerable to attack from above by German fighters who selected the most advantageous position and timing. The ineffectual early tactical doctrine of the American units required the P-38s to fly near the bombers at all times rather than to defend aggressively or to fly ahead and clear the airspace for the bombers, and many American pilots were downed because of this limitation. Losses mounted, and all available P-38s in the UK were flown to North Africa to restore squadron strength. After this painful experience, the American leadership changed tactics, and in February 1943 the P-38 was given free rein in its battles.