Did you think Eren was dumb? Well, think again: the lead in this one is way dumber.
Sweet heavens. It's a great manga thus far but why, oh why, would he do half of the things he does...and why does the Survey Corps go "explore" anything outside the walls with no actual gear!
What is the plan here? Seriously, what is the plan?
They all set out and the moment they encounter a titan they of course had to retreat, immediately, because no only have they yet to develop 3D maneuvering gear as I'm not even sure they know where to strike a titan in order to kill it.
So the idea seems to be, "We go out on an expedition outside the walls, you know, where the Titans are but hope we do not find one. If we do, we scramble like mad back to Wall Maria because we have no actual means- at all- of killing a single Titan. Sounds like a great idea, let's go!"
Erwin's maddest plans had a greater survival rate than this!