The event that occurred just before the Battle of Gettysburg, impacting the Confederate strategy, was The Battle of Chancellorsville.

Fought in May 1863, this Confederate triumph led by General Robert E. Lee lifted Southern spirits and inspired Lee to advance the war into Northern territory. The victory at Chancellorsville motivated Lee to initiate an invasion of the North, as he believed that a significant win could influence public sentiment in favor of the Confederacy and possibly gain foreign recognition. This bold strategy ultimately reached its peak at the Battle of Gettysburg just a few weeks later.