In 1915 Germany promised to restore the boundaries according to the Treaty of San Stefano and Bulgaria, which had the largest army in the Balkans, declared war on Serbia in October of that year. In the First World War Bulgaria decisively asserted its military capabilities. The second Battle of Doiran, with Gen. Vladimir Vazov as commander, inflicted a heavy blow on the numerically superior British army, which suffered 12,000 casualties against 2,000 from the opposite side. One year later, during the third battle of Doiran, the United Kingdom, supported by Greece, once again suffered a humiliating defeat, losing 3,155 men against just about 500 on the Bulgarian side. The reputation of the French army also suffered badly. The Battle of the Red Wall was marked by the total defeat of the French forces, with 5,700 out of 6,000 men killed. The 261 Frenchmen who survived were captured by Bulgarian soldiers.