Chatham Manor. On the opposite side of the Rappahannaok River from Fredericksburg was over taken as a command post and make shift hospital by the Yankees Prior to the battle. Burnsides could have have a quick victory had he been able to cross the river quickly but due to a mix up in orders to build the pontoon bridges the crossing into Fredericksburg was delayed allowing Stonewall to march from the Shenandoah valley and get into position before they tried to cross.
Burnside seemed to have a problem crossing bodies of water. He drug around at Sharpsburg attempting to cross Antietam Creek on what they started calling "Burnside's Bridge" as Georgia sharpshooters on the opposing bluff inflicted over 500 casualties while only suffering about 160 of their own. The bloody lane, Miller's cornfield and the Hagerstown Pike at that battle are depressing places to walk through due to the carnage that occurred there.
Burnside wore these huge mutton chop sideburns and they are the reason that part of a man's head is now called "sideburns".