The second-in-command of a company , squadron or artillery battery ( in which he or she is called the battery captain ) is usually a captain ( although infantry company second-in-commands were usually lieutenants until after the Second World War ) , the second-in-command of a platoon or troop is the platoon or troop sergeant , and the second-in-command of a section is usually a lance corporal .
The Second-in-Command of a smaller group is usually a Captain ( although infantry groups ' Second-in-Command 's were usually Lieutenants until after the Second World War ) , the Second-in-Command of an even smaller group is the Sergeant of the group , and the Second-in-Command of a section is usually a Lance Corporal .