‘The time of their lives’: The RAF’s Pursuit of the Bulgarian First Army, 21–29 September 1918
By: Raf Casps
Tags: Airpower, Military History, History, WIB History, World War I

A week after the RAF’s destruction of retreating Turkish armies at Megiddo, three of its squadrons routed Bulgarian forces who were retreating from the Doiran-Vardar line after the final Allied offensive on the little-known Macedonia front.

The Macedonia Campaign

The Macedonia (or Salonika) Campaign followed an Entente attempt to aid Serbia against attack by Germany, Austria-Hungary and Bulgaria in October 1915. Unfortunately, the intervention came too late to save Serbia, though a front was soon stabilised running from the Albanian Adriatic coast to the Struma River, where a French-led Allied force faced a predominantly Bulgarian army (supported by the German Air Service). There was relatively little fighting between ground forces from early 1917 until the Allied offensive in September 1918. The British Defence Attaché in Belgrade recently outlined the Macedonian campaign as part of the centenary commemoration, though without mentioning British air service involvement.

The British Salonika Force initially relied on Royal Naval Air Service (RNAS) aircraft, based in the Aegean, for air support but when Lieutenant General George Milne took command in May 1916 he requested two Royal Flying Corps (RFC) squadrons. First to arrive was No 17 Squadron in July 1916, fresh from action against the Senussi in the Sudan,[1] followed by No 47 Squadron in September. They faced the challenges of extreme weather, malaria, and obsolete aircraft (such as the BE2c tactical reconnaissance aircraft, and DH2 and Bristol Scout fighters) as well as the modern German Halberstadts of Kampfgeschwader der Oberste Heeresleitung Eins (Kaghol 1), a front-line tactical bomber wing. Kaghol 1’s air raids were particularly destructive until the unit was withdrawn to bomb London in May 1917; raids which lead directly to the formation of the RAF. Even the prevailing winds favoured the Germans, blowing as they did from NNW against the British. To address the imbalance, the RFC resorted to ingenuity, when it killed a German air ace using a kite balloon filled with explosive and a dummy observer, which was detonated as he attacked it.[2]

The German Air Service cedes control of the air

By April 1918 the reinforced and re-equipped 16th Wing RAF had three squadrons to support Milne’s two British corps. No 150 Squadron RAF had a mix of SE5a and Sopwith Camel fighters, and No 17 and 47 Squadrons were equipped with both Armstrong-Whitworth tactical reconnaissance aircraft and, by August 1918, the DH9 day-bombers Milne had wanted.[3] With higher priorities elsewhere, however, the Allied Supreme War Council would not permit a ground offensive and so the RAF was Milne’s ‘only medium open to him’ to attack the enemy. The RAF did so by bombing enemy aerodromes, ammunition dumps and railways in formations of up to fifteen aircraft. A British-led large-scale raid in May tested the Allied Salonika Force’s new Greek allies, captured 1,812 prisoners and was useful combined arms training for both the ground forces and 16th Wing.[4]

An Armstrong-Whitworth RK of No 47 Squadron RAF at Salonika ©AHB

The RAF contributed to the Allied Salonika Force’s preparation for the anticipated offensive and trained for combined arms operations using the latest Western Front doctrine. For example, the 12th Battalion Argyll & Sutherland Highlanders practised communicating with contact patrol aircraft on 15 September and each infantry battalion headquarters was equipped with a Popham Panel — a large foldable cloth panel on which letters and symbols could be displayed — for ground to air communication.[5] Headquarters 16th Wing was collocated with Milne’s at Salonika.[6] The RAF used the long range of the DH9’s to photograph the enemy’s rear areas to produce detailed maps; this aerial reconnaissance indicated that the enemy expected the Allied attack to be in the Vardar valley, opposite the British corps. Meanwhile the RAF’s tactical reconnaissance assisted the artillery to register targets.[7] The opposing ground forces were roughly equal, however, whereas the Allies had 200 aircraft, the enemy had only 80.[8] The final air engagement of the campaign was on 18 September, when four British fighters, protecting a contact patrol, were attacked by five German aircraft. The British took the day, shooting down two of the German aircraft. The German Air Service, subsequently, ceded control of the air, and flew no further sorties.[9]

‘No Rest for the RAF or Bulgar’

The Allied offensive opened on its western flank on 15 September when Serbian and French troops surprised the Bulgarians by storming the mountains of Vetrenik and Sokol with the aim of breaking through and cutting the Bulgarian’s only railway line to the Front. To prevent the Bulgarian First Army being moved west, British and Greek divisions of XII and XVI Corps attacked around Lake Doiran on 18 September. No 47 Squadron co-operated with XII Corps during the attack, and No 17 with XVI Corps, each with flights allocated to artillery observation and contact patrols. No 47 Squadron’s ten aircraft made 151 wireless ‘NF’ calls for neutralising fire, and lost only one aircraft and its crew to enemy anti-aircraft fire.[10] There was an interesting diversion on 19 September when 17 and 47 Squadron were asked for volunteers to land an infantry officer and sergeant behind enemy lines; the mission failed with one aircraft lost and its pilot captured.[11] Though the Bulgarian First Army held, the Bulgarian commander-in-chief, General Gregori Todorov, ordered a general withdrawal. On 21 September the RAF reported columns of enemy troops and guns streaming up the Vardar and Strumica valleys.

The Macedonian Front September 1918 @ Crown Copyright[12]

Although the British corps’ advance was temporarily to recover after the costly assault, ‘there was no rest for the Royal Air Force or Bulgar’ and according to the RAF’s official historian H A Jones who had won the MC as an observer with No 47 Squadron earlier in the campaign, the officers of that Squadron ‘had the time of their lives’ pursuing the Bulgarians. Though the German Eleventh Army had been smashed in the Franco-Serbian attack to the West, the Bulgarian First Army started its retreat in good order but was soon under attack by waves of RAF aircraft. According to Jones, the worst execution was in the choked narrow defile of the Kosturino Pass which was attacked by twenty-five aircraft on 21 September. After the road was captured by advancing British troops, two officers from No 47 Squadron inspected ‘the enormous damage done to the retreating columns, both actual and moral’ and telegrammed to Milne:

The routes from Cestovo Valley to Kosturino show signs of indescribable confusion that must have existed in the retreat of the Bulgar Army. Guns of all kinds, motor-cars, machine-guns, rifles and every kind of war material abandoned. Dead animals are strewn every. Indicating that our RAF must have contributed largely this state of things.[13]

The RAF’s attacks then moved north to the Kresna pass on the 27, 28 and 29 September where similar damage was done. The Bulgarians sent negotiators through British lines to Salonika on 26 September and an Armistice was declared at midday on 30 September.[14]

Addendum

It is also worth noting a third RAF pursuit, in addition to Megiddo and Macedonia, the following month on the Italian Front. On this occasion the four squadrons of 14th Wing RAF pursued Austrian troops retreating from the final Vittorio Veneto offensive until the Armistice of 4 November, dropping 20,000 lbs of bombs and expending 51,000 rounds of machine gun ammunition.[15] Finally the Bulgarian Armistice was only a temporary break in combat for No 17 and 47 Squadrons as they were redeployed from Bulgaria and Constantinople to South Russia in April 1919 to assist White Russian forces against the Bolsheviks.