[Rules] Loading transport in an assault hex

[campsawyer]

I understand the flow of your situation, but I would also ask why was the AT gun forced to retreat and why not force the Germans to eliminate it in the hex. The the Bren is a decent unit to hold up the Germans for a turn or two while they have to mass troops for the assault. So go a head and load the AT, but then wait for the Germans to assault it, don't move unless forced by a demoralization. As noted, these guys are likely to die, but with a DF of 6 the Bren can have a decent chance of a cheap M, M1 or M2 that might throw the Germans off and trigger a disruption or even better a demoralization. Then the next turn sneak them out with a lower German "free shot". Worst case is what happened to you, but everything else is a plus to the British, ie, German delay/tied up, lucky demoralization or possible escape.