On 17 September 1912, the Bulgarian Tsar Ferdinand declared the general mobilization of the army. The order was relayed to Kiselov and accepted with great joy by him and his soldiers. Within six days the regiment was fully mobilized and could field 70 officers, 4 clerks and 4716 soldiers in four battalions and armed with 4,476 rifles or carbines, 4 heavy machine guns and 29 sabers. On 4 October, the 8th regiment marched out of Varna towards the assembly area of the 4th Preslav Infantry Division, to which it belonged. The 4th Division was assigned to the Bulgarian Third army under General Radko Dimitriev which was tasked with the attack on the fortress of Kirk Kilisse. Colonel Kiselov's regiment was part of the divisions vanguard when it advanced into Ottoman territory and was soon engaged in heavy fighting around the village of Seliolu. The Bulgarians managed to defeat the Ottomans in the Battle of Kirk Kilisse but did not pursue immediately their retreating opponent. Thus the Ottoman were able to entrench on a new defensive further south, around Lule Burgas. Thus the 4th Division and its regiments found itself involved in the thick of the fighting once again. The battle was so ferocious that at some point the determination of the soldiers of the 8th Regiment wavered. Colonel Kiselov understood this and decided to bolster the morale of his troops by making a personal example of bravery. So he rode forward and personally led the soldiers in the attack. The Battle of Lule Burgas once again ended in Bulgarian victory but it had inflicted on the victor some 20,000 casualties, so the Bulgarian High Command ordered the troops to reorganize and rest for another several days. Following this battle the fourth division participated in the fighting on the Chataldzha line and remained on that line until the end of the war.