You have to conceive of the plan first. Grant did that.
Once across he defeated two confederate armies and drove one of them back into the city of Vicksburg.
Only because he had the Navy to call on. Could he have defeated these two armies without being carried around to the back of them?
If the situation were reversed, could Grant have won when someone brought in their Navy assets to ferry their troops and logistics into a position where they could not get otherwise?
Grant won because he had the Navy. He could not have won with an even contest.