Battle of Doiran ( 1917 ) During the Second conference of the Military Counsel of the Entente in Chanties , it was decided to continue with the attempts at a breakthrough . The task for the Entente forces on the Macedonian Front was to inflict major defeats on the Bulgarian army and effect a wide breakthrough in the Balkans in a relatively short time . The Allied command , which expected reinforcements , planned a major assault in the direction of Vardar and Doiran . In 1917 the 2nd ( Bulgarian ) Thracian Infantry Division was replaced at Doiran by the 9th Pleven Infantry division under the command of Colonel Vladimir Vazov . Initial attacks . On 9 and 10 February the Allies attacked the 33rd Svishtov and 34th Troyan Regiments but were repulsed by a decisive counter - attack by the Troyan Regiment . The British advance on 21 February was repulsed by Bulgarian artillery after a two day battle . The Allied command found that the Bulgarian positions were better fortified than in the previous year , so it ordered a systematic artillery barrage on these defences . In the meantime , it continued the development of their forming - up ground which was 800 - 1 , 500 m from the defensive lines of the Pleven Division . To make the breakthrough , the British concentrated three divisions ( the 22nd , 26th , 60th ) , with its artillery - more than 43 , 000 men , 160 guns , 110 mortars and 440 machine - guns . The objective did not differ much from the battle in the previous year , the main blow was on a front of 5 – 6 km towards Kalatepe . The prognosis of the Bulgarian command for a major Allied offensive was confirmed by intelligence . The 9th Pleven Division was reinforced and had a total of 30 , 000 men , 147 guns , 35 mortars , 130 machine - guns . According to the orders of the High Command the front was divided into three zones with different widths : the right from the River Vardar to the Varovita heights with a width of 13 km , was defended by 1st Brigade ( 6 companies with 48 guns , 12 mortars and 56 machine guns ) ; the central from the Varovita heights to the Karakondzho heights , 4 km wide , defended by the 57th Regiment ( 3 companies ) and the left from the Karakondzho heights to Lake Doiran , 9 km wide , defended by 2nd Brigade ( 6 companies , 76 guns , 19 mortars and 52 machine - guns ) . Defensive positions . In 1917 the Bulgarian defensive positions and fortifications were further improved . It included two main positions with two rows of continuous trenches 1 , 5 – 2 metres deep , 200 to 1000 m apart and linked with passages for communication . In front of these positions there was a two line system of wire entanglement s . Between the rows of trenches watch points , shelters , machine - gun nests and sunken batteries were constructed . Behind these defences there were concrete galleries , fire positions for the artillery and platforms for ammunition . In front of the main position there were smaller fortifications , with a partly constructed secondary position 2 – 5 km to its rear . The battle . The battle for a breakthrough in the Bulgarian positions began on 22 April and continued intermittently until 9 May 1917 . The assault began with a bitter four - day artillery barrage in which the British fired about 100 , 000 shells . As a result , the earthworks and some wooden structures in the front positions were destroyed . The Bulgarians also opened fire from the batteries between Vardar and Doiran . Vladimir Vazov ordered fire day and night on the Allied positions . The initial several - hour struggle between the British and Bulgarian batteries was followed by a one - hour Bulgarian counter - barrage in which 10 , 000 shells were fired . The British infantry began its attack on the night of 24 – 25 April - 12 companies attacked the Bulgarian 2nd Brigade and after a bloody fight managed to take the " Nerezov " , " Knyaz Boris " and " Pazardzhik " positions . After a Bulgarian counter - attack the British were repulsed with heavy casualties and by 8 pm had retreated . The British assaults on the right and central fronts were also repulsed with heavy casualties after help from the Bulgarian artillery . The British attacks in the next two days were defeated by constant Bulgarian fire and counter - attacks . Due to this fire the British withdrew to their initial positions on 27 April , the Bulgarians immediately started to reconstruct the destroyed fortifications . Due to criticism by their high command , the British made new attempts at a breakthrough . On 8 May , after a long artillery barrage , they began another attack . The main assault started at 9 pm with five waves of British troops attacking the Bulgarian positions . After four attacks during the night of 8 – 9 May the British were defeated and suffered enormous casualties . A " Times " correspondent wrote that the British soldiers called the " Boris " point " the valley of death " . The artillery duel continued until 9 May but due to heavy casualties the British had to abandon all attacks . They lost 12 , 000 killed , wounded and captured of which more than 2 , 250 were buried by the Bulgarian defenders . The losses of the Ninth Pleven Infantry Division were 2 , 000 of whom 900 died from disease and wounds . Vladimir Vazov was promoted to Major - General . Aftermath . In the next 16 months , the front was relatively quiet apart from local skirmishes . Both sides used that time to further strengthen and consolidate their positions . In 1918 a massive Anglo - Greek attack was repulsed by the Pleven Division in the Battle of Doiran .