Complex sentence: The recruiting drives brought the BFC to a strength of 23 men, which worried Freeman because if the unit reached 30, the BFC would be incorporated into the 5th SS Panzergrenadier Division Wiking and sent into action.
Split into simpler sentences: The recruiting drives brought the BFC to a strength of 23 men. This worried Freeman because if the unit reached 30, then the BFC would be incorporated into the 5th SS Panzergrenadier Division Wiking and sent into action.