<P> In the Helles sector, which had been extensively entrenched by both sides, the Allies attacked Krithia and Achi Baba again, in the Third Battle of Krithia on 4 June, with the 29th Division, Royal Naval Division, 42nd Division and two French divisions . The attack was repulsed and with it, the possibility of a decisive breakthrough ended; trench warfare resumed, with objectives being measured in hundreds of yards . Casualties were approximately 25 percent on both sides; the British lost 4,500 from 20,000 men and the French 2,000 casualties from 10,000 troops . Ottoman losses were 9,000 casualties according to the Turkish Official History and 10,000 according to another account . </P> <P> In June, a seaplane carrier HMS Ben - my - Chree arrived and the Allied air effort increased from a squadron to No. 3 Wing RNAS . The 52nd (Lowland) Division also landed at Helles in preparation for the Battle of Gully Ravine, which began on 28 June and achieved a local success, which advanced the British line along the left (Aegean) flank of the battlefield . Sanders credited the defence to two Ottoman officers, Faik Pasa and Albay Refet . On 30 June, the French commander, Henri Gouraud who had earlier replaced Albert d'Amade, was wounded and replaced by his divisional commander, Maurice Bailloud . Between 1 and 5 July, the Ottomans counter-attacked the new British line several times but failed to regain the lost ground . Ottoman casualties for the period were estimated at 14,000 men . On 12 July, two fresh brigades from the 52nd Division attacked at the centre of the line along Achi Baba Nullah (Bloody Valley), gained very little ground and lost 2,500 casualties out of 7,500 men; the Royal Naval Division had 600 casualties and French losses were 800 men . Ottoman losses were about 9,000 casualties and 600 prisoners . </P> <P> At sea, the submarine E14 made two voyages into the Marmara . The third tour began on 21 July, when E14 passed through the straits despite a new anti-submarine net placed near the Narrows . The next attempt was made by Mariotte on 27 July, which was caught in the net, forced to the surface and bombarded by shore batteries; Mariotte was scuttled . On 8 August, E11 torpedoed the battleship Barbaros Hayreddin with the loss of 253 men and sank a gunboat, seven transports and 23 sailing vessels . </P> <P> The failure of the Allies to capture Krithia or make any progress on the Helles front, led Hamilton to form a new plan to secure the Sari Bair Range of hills at the Battle of Sari Bair and capture high ground on Hill 971 in the Battle of Chunuk Bair . Both sides had been reinforced, the original five Allied divisions having been increased to fifteen and first six Ottoman divisions to sixteen . The Allies planned to land two fresh infantry divisions from IX Corps at Suvla, 5 miles (8.0 km) north of Anzac, followed by an advance on Sari Bair from the north - west . At Anzac, an offensive would be made against the Sari Bair range by advancing through rough and thinly defended terrain, north of the Anzac perimeter . This would be achieved by an attack on Baby 700 from the Nek by dismounted Australian light horsemen from the 3rd Light Horse Brigade, in concert with an attack on Chunuk Bair summit by New Zealanders from the New Zealand Infantry Brigade, who would traverse Rhododendron Ridge, the Apex and the Farm . Hill 971 would be attacked by Gurkhas of the 29th Indian Brigade and the Australians of the 4th Infantry Brigade . The Allies had 40 aircraft, mainly from 3 Wing RNAS at Imbros, which had replaced its Voisins with Farmans and Nieuport Xs; Escadrille MF98T had also been established at Tenedos . The Ottomans had 20 aircraft, of which eight were stationed at Çanakkale . Allied aircraft made reconnaissance flights, spotted for naval guns and conducted low - level bombing of Ottoman reserves as they were brought up to the battlefield . Allied aircraft also undertook anti-shipping operations in the Gulf of Saros, where a seaplane from HMS Ben - my - Chree sank an Ottoman tug with an air - launched torpedo . </P>

Where did the main battle between forces from the british empire and turkey occur in 1915