Defend Spargus from attack is a mission in Jak 3. Damas called Jak over the communicator, saying the scope had seen major movements over the water. With Jak being the best gunner, he needed him back at Spargus to defend the city.
The PlayStation 3 and Vita versions of this mission are related to a trophy named "Shoot 'em High", completing this mission will reward you with a bronze trophy.
At the Spargus gun turret you will soon enough be attacked by gigantic walkers, large Dark Maker war machines that attack by firing dark eco bombs at you. Shoot the bombs down to avoid being hit, the walker's only weak points are the joints on their knees, shoulders and the top of their head. These are all marked by reticules and take three shots each to go down. Gun down the first wave of walkers and the turret automatically turns around, facing the city.
Here the last couple of walkers will appear, this time they fire slow-moving missile. Shoot these down to finally fend of the Dark maker assault.