I'm not sure that 'victory' is necessarily implied, but it certainly could. It simply means that nobody or nothing is standing in your way. "Go for it!"
It comes from military parlance. It refers to a battlefield, when armies lined up against one another the tactics were usually to outflank or push back your opponent so you gained control of the field. A subordinate would then say to the victorious commander "Sir, the filed is yours" meaning the battle was won. I would use it in the sense that you have been successful in some effort and I suppose