The mission begins showing Edward Carlyle and Sgt. Starkey crouching behind their crashed jeep and shooting at the German positions. Starkey gives Carlyle some C4 and tells him to plant it at the entrance to prevent the Germans from coming into the fortress. Starkey goes around to the left and Carlyle is left with a couple of Allied soldiers. These soldiers can be really helpful as if you crouch behind the wall and wait long enough one of them will die and drop a Bren which can be picked up. It is advisable to go around to the left and up the stairs, as two allied NPC's, a case of Bren ammo and a Health Pack can be found here. One of the soldiers will say "We're coming with you," and both will follow you. They will often die but are good to draw enemy gunfire.
Flanking around is in easy way to take out the German MG42 positions. After you do this, you can get on the machine gun and mop up any remaining enemies before planting the C4 and blocking the entrance. After you do this, you will be given a new objective that tells you to rescue Sgt. Dehart from the tower at the corner of the fortress. There will be a machine gun position inside the tower. A Grenade would make short work of him. After climbing some stairs, you find Sgt. Dehart and Pvt. Rowe upstairs. There will be a Health Pack and lots of Sten ammo. Sgt. Dehart will tell you that the Germans captured one of their men and took him underground. You will then go downstairs and outside, where massive amounts of German soldiers will be coming out of the other entrance (not the one you took out with C4.)
You will be given a new objective in which if Sgt. Dehart dies you will fail the mission. As you are walking towards the entrance, German bombers fly over and drop bombs all over the area. Here, it is best to go prone and deploy your Bren if you have one. After holding off huge amounts of enemies, the entrance will start blowing up and the objective will read, "Reinforcements have arrived." You will then have to blow up an enemy Half-track with C4. After that you will storm a cistern controlled by the Germans.
After killing the last few enemies, you will go downstairs and find the POW on a bench. The POW will grumble about how it took so long for them to get there and Sgt. Dehart will reply with, "Well, we had a few errands to run." Right before you leave, Starkey will stumble in and ask Carlyle if he was just gonna leave him out there. The remaining soldiers walk through a tunnel and the mission ends.