After the disastrous battle, Pope blamed his misfortunes on McClellan, Franklin, Porter and several other generals and Porter was an especially easy target. The charges against Porter were:
- Disobedience of orders under the 9th Article of War, specifically
- Disobedience to the order of August 27th, requiring Porter to march from Warrenton Junction at 1 a.m. of the 28th and be at Bristoe Station by daylight.
- Disobedience on August 29th, to the joint order to McDowell and Porter, directing them to march toward Gainesville and establish communication with the other corps.
- Disobedience on August 29th, the 4:30 P.M. requiring Porter to attack the enemy's flank and rear.
- Misbehavior before the enemy under the 52nd Article of War.
- I will summarize this time because it's the same thing three times over: basically, the charge accuses Porter of shameful disobedience for not bringing his men into action on August 29 when there are the sounds of battle.
To actually discuss the events:
Charge #1A: Pope had been pushing north to Manassas after Jackson had raided the Orange & Alexandria Railroad, pushing his army hard. Learning from prisoners following a skirmish between Hooker and Ewell that Jackson was in front of Manassas, Pope wanted to close the distance ASAP. The whole army would march for Manassas through night and day. It was a mess from start to end for all units. In Porter's case, he set the time for 3:00 A.M. and his lead units arrived at Bristoe Station about 10:00 A.M. Porter blamed this
delay on the moonless night, wagons blocking the road, and the fatigue of his men.
Charge #1B: This was after the fight at Brawner's Farm. Believing he had Jackson right where he wanted him, Pope needed to make sure Jackson could not get out. Hence, Pope ordered both McDowell and Porter toward Gainesville. At Dawkins' Branch, however, Porter ran into Stuart's cavalry, screening Longstreet's advance. Soon, McDowell brought information that Longstreet had arrived with the rest of Lee's army and was between Porter and Gainesville. McDowell told Porter to decide to fall back, stay where he was, or attack while McDowell himself took his troops to join Pope and hopefully link up his left with Porter's right. Porter stayed in place, unintentionally forcing Lee to pause his plan to attack on the 29th. However, this leads to...
Charge #1C & Charge 2: Pope did not know Longstreet had arrived, for McDowell did not pass that news along to him. He therefore
Porter to attack Jackson's right flank. Pope was very much counting on Porter to come in and save the day after many fruitless attacks on Jackson. The order came fairly late at 6:30 P.M. Given that Porter was not in fact looking at Jackson's flank, this is of course not very practicable and no such attack was made.
Porter's actions on the 29th especially incensed Pope and were the easiest to find fault in, especially with Pope's faulty understanding of Longstreet's presence. Nobody could say Porter did not attack weakly on the 30th and with much confusion about Confederate dispositions, it was easy to present Porter as disobedient in the face of the enemy.
Porter's first step to redemption was the Schofield Board in 1878, which concluded in March 1879 with the recommendation to throw out the court martial findings and restore Pope to his position in the army. When that wasn't acted upon, Grant came out in 1881 to call for Pope to be exonerated. Grant's article can be read
here for free. He was pardoned but received no restoration to the army. Ultimately, Porter had to wait for a Democrat administration to be restored to his old position.