John Brown was practically faking the fatality of the wound and was able to move so when the soldiers left him to "die" he was able to get up and get escape. he was also assisted by some of his own soldiers that survived.
Haha brown will strike again!
c'mon sir we have to get you back to safety!
Hey! Stop right there you are under arrest. You are being executed sir, for the bad you have done to us.
On the way back to Brown's safety he gets captured by his enemies and he then gets held hostage and is executed.