This mission is relatively short, and works essentially as an introduction and tutorial, with many cutscenes (which disrupt flow and unit-control). I doubt it’s possible to lose.
You start with one six-man rifleman squad sheltering behind a tank trap in shallow water at the worst section of Omaha Beach. Your first goal is to get 25 men to the ridge or “shingle” at the top right portion of the beach, where indicated. To do this, send your initial unit (directly or via areas of cover) to the shingle area, and keep selecting different yellow American units (which turns them blue, indicating you control them) and sending them to the shingle until 25 are there.
Sniper units are particularly valuable as they can snipe German HMG crews from range, but they must be kept in “camouflage” mode to minimize their risk of being shot.
Once you get groups of American troops totaling 25 soldiers to the shingle, you’ll be told to select and bring up to the shingle an engineer crew. Do this.
When your engineer squad reaches the shingle area, there will be another cutscene, in which the engineers blow a hole in the wire, opening a path up past the bunker. Most of the units you brought to the shingle will now disappear, leaving you with just two or three squads—plus the sniper if you are lucky.
Try to take out the two HMGs in front of the bunker using your sniper and/or rifleman squads with grenades. Of course, it makes no sense that these soldiers can even lift their heads without being riddled with mg rounds. But your rifleman squads and sniper (if still alive) eventually should be able to grenade/snipe those first two machine-gun positions.
When those HMGs are de-crewed, send the engineer squad up to the spot just below the bunker and have the squad toss a satchel charge into the bunker. It will explode, there will be yet another cutscene, and you will be able to get your troops up the slope to the area behind the bunker.
The mission now becomes easy: Have one of your rifleman squads pick up the LMG lying behind the bunker. Use it to wipe the German infantry in the nearby dugout path. Grenade the crew of the 88 overlooking the beach. Recrew that 88 and use it to take out all the German units covering the left side of the beach (this gets you the medal). Move your units to the upper left of the map, flanking and grenading/satchel-charge-demolishing HMGs, bunkers, and the back-left 88 (which must be destroyed, not re-crewed). Pick up LMGs when you can. Work your way across the back of the map and demolish the remaining 88. If you want, achieve the secondary objective of taking out at least four bunkers (with satchel charges) before destroying the last 88. When that last 88 is gone, the mission ends.
Note that when your squads are in the dugout paths that run amid the fortifications, they may have major pathing problems. To minimize these problems, use the pause button frequently, refrain from selecting multiple units for movement, and keep your units as widely separated as possible.