The obvious POD here is that Jackson survives infection following his severe wounding and subsequent amputation of his left arm following Chancellorsville in May 1863. One of the ACW's most potent alternate history questions regards Jackson being present at Gettysburg (The reorganization of the ANV into three corps is another question), and it is generally agreed that he would have either seized the high ground on the evening of the First Day and succeeded, or have joined in Longstreet's protests to withdraw to defensive terrain of the Confederates' choosing and forcing Meade, under heavy political pressure, to attack. If Jackson did survive, I think he'd end up like Longstreet in OTL after he was gravely wounded in a similar manner at the Wilderness a year later. That means he convalesces in Charlotte, NC, with his family and doesn't return to field service until October/November of 1863 (In time for the Bristoe/Mine Run Campaigns, assuming the War follows the same course in the summer and fall). When Jackson returns and re-assumes command of his Second Corps from the controversial and incompetent Ewell, what happens to the latter? Southern morale may be higher in Jackson's presence, especially among the officers. I personally would have Jackson at Mine Run (Although Meade is still unlikely to attack), where Lee thought a 'Second Chancellorsville' was possible. And a Confederate victory in the East at that time could have had interesting political consequences for the following year. And if nothing except Stonewall surviving changes 1863, how does Grant's Overland Campaign develop the following year?