Only if you ignore his performance prior to that. Grant had commanded armies since the beginning of 1862, had outmaneuvered his opponents and captured two whole armies in the field at Fort Donalson and at Vicksburg, cut the Confederacy in half, and beaten every general Davis sent against him.
If he was a genius, he would have also been a President with memorable accomplishments. Instead he was a one termer.
Grant served two terms.
He and General Sherman orchestrated Sherman’s “March to the Sea” which was a scorched earth policy that instituted a war on civilians in order to cut off supplies to the Southern armies.
And your point is?
There was no Southern invasion of the North and there was little to no Southern support for it until Gettysburg.
You seem to be forgetting Lee's campaign in Maryland in September 1862.
That only took place after Sherman’s March.
Gettysburg was July 1863. Sherman's March was the autumn of 1864.
Having groups of Naval vessels which he could use to ferry his troops across the river made that possible. Once again, his great victory is more of a function of having superior assets to call on, and not so much due to his own abilities.
What would he have been able to do to take Vicksburg without those ships?