Complex sentence: The total strength was 68 Marines and 11 sailors, which was greater than would normally have been available because the garrison was in the process of changing over-both the replacements and the troops preparing to leave were in the Falklands at the time of the invasion.
Split into simpler sentences: The total strength was 68 Marines and 11 sailors, which was greater than would normally have been available because the garrison was in the process of changing over. Both the replacements and the troops preparing to leave were in the Falklands at the time of the invasion.