Your current task: Protect the camp
Scramble! Your camp is being attacked. Arm yourself up and get rid of the enemies.
Your current task: Kill the minigun-soldiers
Meet the minigun soldiers. There are just two of them, so you should take them out with ease.
Your current task: Help Slade during attack
It's time to face the enemy soldiers outside the base. You can try to familiarize yourself with the minigun. Kill the MG soldier with the rocket launcher and pick it up - you will need it soon.
Your current task: Get back to the camp.
And just as you are suppose to get to the base - the walking tank will appear. Run like hell to the camp to get the rockets. Now - plan is simple - find a hiding spot, aim and destroy this piece of metal.