On December 31, 1862, the first day of the Battle of Stones River, Confederate General Braxton Bragg made a surprise advance on his left and drove the right of the Union army of Major General William S. Rosecrans back three miles. At that point the Union line was nearly at right angles to its original position. The brigade of Col. William Babcock Hazen defended a clump of cedars—known locally as the Round Forest—at a salient in the line just east of the Nashville Pike and on both sides of the Nashville &amp; Chattanooga Railroad. Hazen's men, supported by other Union troops, and especially by artillery that Rosecrans had massed on the high ground in their rear, successfully repulsed four Confederate assaults. So great was the slaughter that soldiers called the place "Hell's Half-Acre." Hazen's regiments sustained 409 casualties (29% of the brigade), including 45 men killed. The determined resistance of Hazen's brigade arguably prevented the Confederate Army of Tennessee from breaking the Union line.