I imagine hunters were still living outside the walls when the attack happened and only a few official hunters were combat ready and veterans. Titans were around for a long time when Twilight Gap happened and warlocks were already busy weaponizing the light. I also think Ana had her own fireteam she led, considering her cloak was called "Strength Of The Pack". Question is the titans and the warlocks tried to break the enemy during the battle. It was not enough. So what did break them?