Colonel was a military rank used by planet-based forces (such as the Imperial Army) as well as certain Starfighter Corps. Colonels ranked below generals and above majors, and were equivalent in rank to the naval rank of captain. In the Imperial Army, the rank of colonel was divided into several grades. Lieutenant Colonels, who could command a regiment of up to 4,000 soldiers, were the lowest rank. High Colonels were the highest rank of colonel, commanding a battlegroup of four to eight regiments. Colonel was also a rank used by Imperial Security Bureau, for example Colonel Wullf Yularen.