In this mission you have to withstand a frontal assault of a lot of enemies storming your position. Before that you have to place your commandos and the considerable number of allied soldiers strategically. There are many possible solutions to this. I just found a very easy one:
Let us assume where your party starts is north and where the enemies are is south. On the western border of the map the most northern wall has on its north side a small gap between itself and a cluster of bolders and trees. Place ALL
your soldiers including your commandos in here lying (press
for the allied soldiers so that they use their backpacks for cover) and facing along the wall eastwards. You can get approximatly 3-4 soldiers next to each other. To get your commandos to fire automatically aim with their weapon (press and hold
) and then press
This method is definitly not very fast but it gets the job done without any interference on your part. You can use The Duke (the sniper character) to shoot enemy snipers when they appear. The last few enemies will run around the map like headless chickens unable to find you. Switch to an allied soldier (they always shoot automatically when an enemy is in their line of sight) and hunt them down by crawling after them.
I hope this helps if you are struggling with this mission which at least for me was very different from how I play this game and thus rather annoying.