Episode-9:
Guess this means humanity is even more fucked because it's implied the Armored and Titan-Titan were humans like Eren and can transform at will. So, they must have sleepers inside the walls already, meaning if they wanted too couldn't they just kill everyone in an instant?
I think if this indeed the case then there would be more to it then that since if the goal is simply destroy all humans then why not just tear down the gates and be done with it? Why wait 5 years between wall breaches?