I'm confused? I thought the Governor had already sent his team to take the Prison. [...]
He approved the raiding party, but they were planning to leave in the morning. Rick and company arrived first.
So, my question is this, is this what happened -
a.) The attack on Woodbury at night
b.) Tyreese's gang finding shelter in the prison the next day
I think Tyreese's group found shelter while Rick and company were en route to Woodbury.