Ctesiphon had been heavily reinforced, but his aircraft was shot down by ground-fire and Reilly captured. It has been suggested in the Official Histories of the Air War and the Campaign in Mesopotamia, that if Reilly had successfully returned with his intelligence to the British lines, Major General Townshend, commander of the British force, would have aborted the attack. After Ctesiphon, the British column retreated to Kut al-Imara, pursued by the Turkish Army, and Kut was besieged from 7 December 1915. Those aircraft that could evacuate left Kut earlier that day, but most of the personnel of the forward deployed A and B flights of the squadron, along with three unserviceable aircraft, were trapped in the besieged town. While reduced in serviceable strength to only a single B.E.2, the Squadron provided reconnaissance support to the force sent to relieve the troops trapped at Kut. The squadron was reinforced by four more B.E.2s in February 1916. The relief column failed to break through to Kut, and in April 1916, the squadron, with eight B.E.2s, together with seven RNAS aircraft, carried out one of the earliest air supply mission when it air-dropped food and other supplies to the besieged garrison. While of food was dropped between 15 and 29 April, this was insufficient to feed the trapped troops and the civilian population of the town, and Major General Townshend surrendered on 29 April. The squadron built up its strength over the summer, and by August had 13 B.E.2s, which were supplemented by six Martinsyde Elephant scouts in September 1916. The squadron supported the resumed British offensive that started in December 1916, which resulted in the British capture of Baghdad on 11 March 1917, with the squadron moving to Baghdad airfield later that day. In April 1917, the Ottoman air defences were strengthened by the arrival of Halberstadt fighters from Germany, which outclassed 30 Squadrons B.E.2s. In response, two Bristol Scout fighters joined the squadron, with the promise that more capable Spad VIIs would follow. In August that year, 63 Squadron arrived in Mesopotamia, so that 30 Squadron was no longer the sole source of air support for the British forces. In September the promised Spads arrived to replace 30 Squadron's Bristol Scouts, while from October Royal Aircraft Factory R.E.8s arrived to supersede the obsolete BE.2s, which were phased out by February 1918. In December 1917–January 1918, the squadron received two Airco DH.4