When you meet up with the French rebels you'll have the choice of going left to the Flak 88s or going through the house to the right. Go left to the guns and kill all the Nazis around the gun and in the ditch leading to the next gun. Then, blow up the 88 and move on to the rest of the guns. After you blow up all the guns you will reach the house that you would have had to go through if had chosen right. When you go in the house you must defeat a Nazi that is there waiting for you. Kill all the enemies in the house and fall through the burning floor. You will find your allies there waiting for you.