Once in the some army

Once in the some army decided to do an audit of people, equipment and jobs for the subsequent modernization of the army. In the process faced with the question: why the sixth person for service Artillery guns, if necessary five people ??? long racked their brains_ _, they decided to dig a little into the past
And, as it turned out, during the time of Napoleon, the sixth man led the horse and pushing a dray with a cannon, which she pulled: -) ????? !!!!!!!