I was a bit worried about this one going in so I figured I'd give you guys my first ever guide to the "Brothers' Keeper" achievement worth 70 GS.
In chapter three, part four "The Somme", you get in a tank with a group of five soldiers following along side. Bi-planes will machine gun and drop bombs as you move forward, always coming from the front. Aim high and go slow and it'll be NO problem. The soldiers will warn you of incoming planes so if you slow down on an incline it'll be a bit easier.
There are three sections. The first and third will have the planes and the second will have you put out a fuse underground and then grenade a bunker. You chase the fuse after going down a ladder and put it out with an A button prompt. The third section will also have bunkers to bomb and only four soldiers along side to protect . Thanks to True Marvelous and LizardKingv666 for noting the four soldiers in the third section.
It should be noted that I died during the defusing section (I was looking for collectables
) and I still popped the achievement.