Don't be surprised that those about to be executed don't fight back even with them outnumbering their captors.
 
They probably went through the most horrifying mental torture that you could imagine.
In cases like these the POWs are sometimes divided into groups and forced to watch false executions of other groups. Executioners prepare the POWs as if they are going to be executed and then shoot next to them, have a good laugh and load them back into trucks. Several 'treatments' make POWs become very docile because they are first shocked, then terrified beyond belief, and finally relieved and reassured that they may live if they bow down. Instant Stockholm syndrome combined with indifference.
When the time for the actual execution comes, they don't even know what's real anymore and they don't care.