Stoneman ordered Burbridge to bring his army of 4,200 men through the Cumberland Gap to join Stoneman and General Gillem at Knoxville , Tennessee where Gillem was refitting his own command into a picked force of 1,500 men . Stoneman ordered Burbridge to bring his division of 4,200 cavalrymen through the Cumberland Gap to join Stoneman and Gillem at Knoxville , Tennessee , where Gillem was refitting his own command into a picked force of 1,500 men .