Losing Vicksburg was more than the South could afford, and Lee's gamble to win a victory in Pennsylvania risked bigger losses. As the year progressed, most of the important military action took place in the center, in southeastern Tennessee, where Braxton Bragg nearly destroyed a Union army and bottled up the remnants in Chattanooga. The North needed someone to reverse Bragg's victory, so they called in Ulysses S. Grant.