War Office takes over air defence

On 16 February 1916 responsibility for the air defence of London passed from the Admiralty to the War Office, the British ministry of war. The guns, searchlights and aircraft defending the capital were placed under Field Marshal John French, who since December 1915 had been Commander-in-Chief, Home Forces. According to the British official history of the war in the air, a few days later the army took over defence against air raids in the rest of the country. The navy kept only the task of engaging enemy aircraft over the sea before they reached the coast.

A year and a half of divided responsibility

From the beginning of the war the defence of the British Isles against air attack was divided between two ministries. In early September 1914, when almost the whole of the army’s air arm, the Royal Flying Corps, was already in France, the government entrusted home defence to the navy and its air service. This was meant to be a temporary arrangement, and both sides treated it as such. The British official historian H. A. Jones wrote that the system suffered from all the defects of divided command: indecision, lack of coordination and conflicting purposes. The Admiralty never fully took the matter on, and the War Office considered that home defence, in the air as well, belonged to the army.

Soon after taking office in May 1915, the new First Lord of the Admiralty, Arthur Balfour, asked the War Office to take over the defence. The army agreed in principle, but had neither guns nor aircraft, so the matter dragged on. In September 1915, after Zeppelin raids on the City, the Admiralty entrusted the gun defence of London to Admiral Percy Scott. He removed the useless small-calibre pom-pom guns from their positions and began building rings of guns around the capital. After the raid on the theatre district in October, the two departments agreed a division of tasks in November: the navy was to engage the enemy approaching the coast, and the army those airships that reached land. The government’s War Committee, however, merely took note of this, and in January 1916 Lord Horatio Kitchener, the Secretary of State for War, withdrew from the agreement, arguing that in view of the needs of the Western Front the army had no guns or aircraft for home defence. The Admiralty expressed “great surprise and regret”, and Balfour had several conversations with Kitchener.

The matter was settled by the raid on the Midlands on the night of 31 January/1 February 1916, which showed that the industrial districts inland were practically defenceless. The War Committee, which had already discussed it on 26 January, returned to it on 10 February. It decided that the army would take over all means of defence on land and would also provide aircraft to protect garrisons and important sites, while the navy would deal with aeroplanes and airships approaching over the sea and patrol the coasts. The British official history of the war at sea dates the army’s takeover of the defence to 10 February, the day of the decision. The actual transfer of command over the defence of London took place on 16 February.

What the army took over

Outside London most of the anti-aircraft guns in ports and at important works were already manned by soldiers, as the army had been responsible for their defence since November 1914. The greatest change was therefore in the capital. According to Jones, at the time of the transfer there were 295 anti-aircraft guns of various calibres in the whole country, 65 of them in the London area. 53 of them were pom-poms of no fighting value, and only about 80 met the War Office’s requirements for an effective anti-aircraft weapon. The War Office staff drew up a plan for the defence of eight industrial areas, from Scotland to Portsmouth, which ultimately envisaged 475 guns and 500 searchlights. For London, Scott’s plans were adopted: two rings of gun positions about 8 and 14 kilometres from the centre, extended to cover the arsenal at Woolwich and the powder factory at Waltham Abbey.

The army was also preparing for air defence by aircraft. From the end of 1915, ten airfields around London each had two B.E.2c aircraft standing by, with pilots trained for night flying, and on 1 February 1916 these detachments were placed under a single commander, Major T. C. R. Higgins of the new No. 19 Reserve Squadron at Hounslow. From then on the Director-General of Military Aeronautics, General David Henderson, supplied French with aircraft just as he did the commanders at the fronts, and air defence plans were drawn up by the staff of Home Forces. The change brought no immediate results, as guns and aircraft were still in short supply, and some of the guns ordered were diverted to arm merchant ships against submarines. By the end of March, however, anti-aircraft fire east of London contributed to the destruction of the airship L 15, and in the autumn of 1916 night fighters began regularly destroying airships over England.