During the winter of 1916–1917, German air tactics had been improved, a fighter training school was opened at Valenciennes and better aircraft with twin guns were introduced. The result was near disastrous losses for Allied air power, particularly for the British, Portuguese, Belgians and Australians who were struggling with outmoded aircraft, poor training and weak tactics. As a result, the Allied air successes over the Somme would not be repeated and heavy losses were inflicted by the Germans. During their attack at Arras, the British lost 316 air crews and the Canadians lost 114 compared to 44 lost by the Germans. This became known to the Royal Flying Corps as Bloody April.