Fredericksburg was a strategic point for both sides. On Dec. 11, 1862, Union troops sneaked forward under the pre-dawn fog to begin building pontoon bridges crossing the Rappahannock River at Fredericksburg, drawing Confederate fire. Union commander, Gen. Ambrose Burnside, then ordered a bombardment opened up on the city. The fierce bombardment lasted nearly two hours as thousands of shells and projectiles rained down on the city. Amid the bombardment, Union soldiers crossed in boats to the other side and block-by-block street combat began — a rarity in the conflict. The full body of federal forces crossed the Rappahannock on Dec. 12, 1862, and Burnside ordered a series of deadly and ineffective frontal assaults on two heights in the city, leaving thousands dead and wounded.
Even though Union forces briefly pierced the main Confederate line, they were repulsed By Dec. 15, Burnside had canceled the offensive and his battered and beaten forces retreated across the river. The fighting engaged some 100,000 Union troops and more than 72,000 troops under Confederate Gen. Robert E. Lee. When it was over, there were more than 13,000 Union casualties and some 4,500 others on the Confederate side. After the Union's defeat, Burnside would be replaced a month later at the head of the Union army by yet another general.
This series marking the 150th anniversary of the Civil War draws primarily from wartime dispatches credited to The Associated Press or other accounts distributed through the AP and other historical sources.From ABC News and the Associated Press