Refused 180 extra men and guns from the Second Cavalry
Deliberately disobeyed orders instead of circling the Wolf Mountains he rode straight across them
Marched through the night and drove his men and the horses hard, arriving at the Little Bighorn a day early
Ignored the warnings of the Indian Crow scouts
Decided to split his forces when attacking the Indian camp
Wanted personal glory at any cost, made hasty decisions and put the lust for a personal victory over the safety of the Seventh Cavalry leading to their defeat
The Bureau of Indian Affairs informed the US army they would be facing 800 warriors, which the three columns could have easily defeated. In reality there was 2000 Indian warriors.
On the 17th of June General Crook decided to halt for a coffee break on the Rosebud Creek. While the officers were playing cards Crazy horse led an attack. By the end of the day Crook had lost 28 men, 63 were wounded and 25,000 rounds of ammunition had been lost.
Reno and Benteen disobeyed Custer's orders to support him during the main attack but they did not do so. Later they said they were unable to as they were under attack.
Terry was right about the location of the Sioux camp however he had underestimated the number of Sioux Warriors. After Crook's battle with Crazy Horse the Sioux had realised that the army was on their trail. Crazy horse and Sitting Bull had joined forces. The cap totalled 12,000 Indians.