I've done some browsing over the last week on events leading up to the main battle. I enjoy learning the ironies, coincidences and what if's of historical events.

On June 26th, 1863, Gen. Jubal Early took Gettysburg on his way to York, PA and the Susquehanna River which he reached on June 28th. Along his way, Early came upon an iron works owned by Thaddeus Stevens, a noted Union abolitioinist. Early, who, like most Confederate troops, did not pillage, loot or burn property. But he made an exception in the case of Steven's forge and burned it to the ground.
June 26 is also the date the first casualty of the battle occurred. A Union soldier ironically named George Washington Sandoe, a member of the Adams County cavalry unit, killed trying to escape capture.
The American Civil War and the Battle of Gettysburg: Private George Sandoe 21st Pennsylvania Cavalry

On June 27th, Joe Hooker resigned as commanding General of the Army of the Potomac under heavy criticism after Chancellorsville. George Meade was named commander on this date, June 28th.

One individual can make a difference and shape events. Here's a story I stumbled across and find interesting. It occurred on Day 3 at the Angle, the center of the Union line and the point of Lee's attack.

Battle of Gettysburg: A key individual makes a difference - YouTube

Gettysburg overshadows the fall of Vicksburg on July 4th 1863.
This really was the week that was for the Confederate Army

Grant took Vicksburg and Lincoln brought him east in 1864 to take command of all Union forces, in effect becoming Meade's superior officer during the 1864campaign.