 Following the Lawrence Massacre Jennison was once again commissioned a colonel and called into service by Kansas Governor Thomas Carney to raise a regiment that would become the 15th Kansas Cavalry on October 17, 1863.Colonel Jennison commanded a mixed brigade of Kansas militia and volunteers resisting Price's Raid in October 1864.However, in December he found himself under arrest as the result of plundering while returning through Missouri after the pursuit of Price.