Consider this, in "Home" when the Governor conducted a small attack on the Prison with Martinez, Shupert, and two other Woodbury soldiers, it had a much bigger impact on the Prison group than his massive attack with 20-25 Woodbury soldiers, several vehicles, and some major weaponry.

Attack in "Home"

- Prison group was left traumatized

-Axel was killed

- The prison yard was flooded with walkers

- Practically burned through all the group's bullets

-One Woodbury soldier was killed (not much to the Governor)

Attack in "Welcome To The Tombs"

-Fence to prison courtyard was bust open

-Entrance to cell block was bust open

-20-25 Woodbury soldiers killed

-All vehicles lost

It makes you wonder what the Governor expected to accomplish from a massive "overwhelming" assault, if the Governor had put more effort into it he could of just wiped out all of the Prison group easily. By keeping those in the courtyard pinned down, they wouldn't be able to rescue Hershel from the walkers. If Martinez came back from the brush he could of gunned down Rick since he was out of ammunition. He also could of gunned down Glenn as he returned from behind the Prison.