Meanwhile , another grand division would distract the Confederate troops by repeating the December crossing at Fredericksburg .
At dawn of January 21 , engineers would push five bridges across ; after that , two grand divisions would be over the river in four hours .
Another grand division would distract the Confederate troops by repeating the December crossing at Fredericksburg .
At dawn of January 21 , engineers would push five bridges across ; after that , two grand divisions would be over the river in four hours .