Complex sentence: There she joined a convoy that sailed for France on 11 February and arrived at its destination on 28 February; "Iowan" discharged her equine passengers--less seven that died or were destroyed during the voyage--at Remount Depot No.3 on 5 March.
Split into simpler sentences: There she joined a convoy that sailed for France on 11 February. The convoy arrived at its destination on 28 February; "Iowan" discharged her equine passengers--less seven that died or were destroyed during the voyage--at Remount Depot No.3 on 5 March.