The U.S special force unit should be a U.S ranger Squad, Six Ranger battalions were raised, all composed of volunteers. The 2nd and 5th Battalion fought heroic at the beaches in Normandy on D-Day. The 2nd battalion scaled the sheer cliffs at Pointe du Hoc, were they destroyed the heavy gun emplacements, dug into the cliffs. The 5th battalion landed on Omaha Beach and let a breakthrough the German lines. The 6th battalion was deployed in the Pacific., were they preformed Ranger mission of recon and raiding behind enemy lines.
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The UDT who pretty much made DDAY possible, sneaking ashore 4 hours before the official invasion and destroying tank traps underwater minds, and barbed wire fences allowing the allied forces a much easier entrance to normandy. The UDT kept on fighting in WW2 but more or less in the pacific. The UDT is pretty much the birth place of the US navy Seals.