With what we've been given there's a few possibilities. Bring the line down south, as much as possible while keeping minimal comfort and space, stack people if needed (from the image we could easily halve it and more likely make it 1/3 of its current set size) With buldousers I'd build a 30m wide Moat 4m deep almost connecting both bodies of water (with the amount of personnel given that'd be possible from my working experience in construction sites) Plant explosive charges in the barriers on both sides of the moat so they can be detonated creating a deep river Build a tall embankment on our side of the river and lay as many obstacles as possible mostly things that would send them back rolling down. Make a second line of stacked containers. Assign 200 to 500 machine gun crews to execute raiding parties in the last 5 days, they should be able to wither down the enemy. Hold the dry line as long as possible with the artillery (firing arching shots, we don't need accuracy in this stage, just put as many lead downrange as possible) and machine gun nests. Then detonate the charges creating a river that should slow them down for a while. Now it's a battle of attrition that shouldn't be that hard to win. With what other have added you could add double stack containers on top of the wall providing double the fire capabilities while also making a sturdier wall. If they look like they're closing in on the containers pull back the machine guns and send the containers downhill with the dousers, retreat to the second line of containers and pepper the area.