491px-Kasserine_Pass.jpg
The 2nd Battalion, 16th Infantry Regiment of the United States Army marches through the Kasserine Pass
In early 1943 US forces met German forces for the first time on any large scale in the Battle(s) of Kassereine Pass in Tunisia.
The Germans breached American lines shortly after the attack which commenced on February 19, 1943. Evidently the final withdrawal by Rommel was due to his worry about the British 8th Army under Montgomery which was at his rear. US forces retook the Pass on February 25, 1943.
African_Mediterranean_European_Theater.png
While the American forces did not fair well against Rommel and company, it was a learning experience for the GI's. They were a green force and had little chance against the battle hardened Germans. Rommel's army used captured US equipment for some time after that. Rommel was unimpressed with American forces at the time and considered them a "non-threat" after that (at least for awhile).
Ironically, earlier in February, 1943 the Germans and their allies had surrendered after their catastrophe at Stalingrad.
703px-Kasserine_pass.jpg