As battle rejoined our only hope seemed to be to cut our way out towards the exit and hope we could escape before the main group of Orcs descended on us. The two Dragonborn brothers took up supporting positions to hold back the Orcs while the rest of the party concentrated on clearing the escape route.
But as the battle progressed we grew in confidence and once our escape route was clear we chose to turn on the offensive rather than flee.
Amazingly (given our groups track record) the tactic worked and we were able to destroy the Orcs piecemeal.
This was a thoroughly enjoyable game (I love it when a plan comes together) made all the more satisfying because we thwarted The Evil GM's plan for a birthday TPK.