Ozerki, but the first wave of attackers were pushed back. The next day, 500 Bolsheviks attacked Shred Mekhrenga but were eventually repelled, with over 100 Red troops being killed despite the British suffering no fatal casualties. Another Bolshevik attack was launched on Seltskoe, but that attack also failed. In total, the Bolsheviks lost 500 men in one day in the two attacks. Many of the British and foreign troops often refused to fight, and Bolshevik attacks were launched with the belief that some British troops may even defect to their side once their commanders had been killed. The numerous White mutinies demoralised Allied soldiers and affected morale. The Allied forces were affected by their own mutinies, with the British Yorkshire Regiment and Royal Marines rebelling at points as well as American and Canadian forces. A major offensive was launched in May in the Murmansk sector. During the advance on Medvyeja-Gora on 15 May, the stubborn Bolshevik defence was only ended with a bayonet charge. British and Bolshevik armoured trains then traded blows as the British attempted to seize control of more of the local railway. The town was finally seized on 21 May, as Italians and French troops pushed forward with the British. The May offensive never quite carried the Allies as far as the largest town in the region, Petrozavodsk. In April, public recruiting began at home in Britain for the newly created 'North Russian Relief Force', a voluntary force which had the claimed sole purpose of defending the existing British positions in Russia. By the end of April 3,500 men had enlisted, and they were then sent to North Russia. Public opinion regarding the formation of the force was mixed, with some newspapers being more supportive than others. The relief force eventually arrived in North Russia in late May–June. On 25 April a White Russian battalion mutinied, and, after 300 men went over to the Bolsheviks, they turned and attacked the Allied troops at Tulgas. In May and June, the units of the original British force which had arrived in Archangel in August and September 1918 finally received orders for home. In early June the French troops were withdrawn and the Royal Marines detachment was also sent home, followed by all Canadian troops after it was requested that they be repatriated. All remaining American troops also left for home. The Serbian troops (perhaps Maynard's best infantry fighters) became