Initially, Wallace's forces along the river at Monocacy Junction consisted of Tyler's brigades and a cavalry force of 230 troopers from the 8th Illinois Cavalry Regiment commanded by Lt. Col. David R. Clendenin. Wallace moved in additional troops to assist them, including the 11th Maryland, a field artillery unit, and Ohio units from Annapolis and Baltimore. Wallace's men skirmished with Early's cavalry west of Frederick on July 7, but later retreated toward Monocacy Junction to avoid being surrounded. Following the skirmishing on July 7 and 8, when Confederate cavalry drove Union units from Frederick, Early demanded, and received, $200,000 ransom to save it from destruction.