Oh, Mon Dieu. That child was a terror. He was mobile by approximately four months, a terrifying three months before any of his brothers had been, rolling and crawling as quickly as he could propel himself to do so.
By six months he was walking and was causing trouble as one could not believe, opening and falling into cupboards, climbing up into trunks (and vanishing until we could find his location via his tearful cries later), and finding his way into every mess and mud puddle and body of water he could locate.
Keeping him alive was a heroic effort in itself.