Where did grant defeat confederate forces first before he could capture Richmond?

Appomattox

At Five Forks, on Apr. 1, 1865, where Sheridan succeeded in shuttering the Pickett's Tactical Group, capturing more than 4,000 prisoners and then interrupting the railroad Richmond-Danville, what allowed the Federals to provoke the collapse of Petersburg's front and the seize of Richmond in the morning of Apr. 3.