I beat it by having 4 men jump on the 50 cal gun emplacements to kill the first wave of infantry, and I had the rest grab mines. After the infantry were dead, I had the men with mines go out about 100 yards from the base and lay mines all the way across the pass in a straight line. If you can command the men fast enough, I think you can lay 12 mines across so that no tank could possibly cross without being killed. I took as a bunch of satchells and placed them about fifty yards in front of the base, again in a straight line. I then had all my guys hide behind the ruins in the back and I hid near the front where I could see the tanks coming. I believe all the armored units were killed by the mines, and when the last wave of infantry got close, I detonated the satchells. I then called my men to return to formation, and they wiped up the remaining infantry.