Advancing deep and fast, the Austro-Hungarians outran their supply lines, which forced them to stop and regroup. The Italians, pushed back to defensive lines near Venice on the Piave River, had suffered 600,000 casualties to this point in the war. Because of these losses, the Italian Government called to arms the so-called "99 Boys" ("Ragazzi del '99"); the new class of conscripts born in 1899 who were turning 18 in 1917. In November 1917, British and French troops started to bolster the front line, from the 5 and 6 divisions respectively provided. Far more decisive to the war effort than their troops was the Allies economic assistance by providing strategic materials (steel, coal and crops – provided by the British but imported from Argentina – etc.), which Italy always lacked sorely. In the spring of 1918, Germany pulled out its troops for use in its upcoming Spring Offensive on the Western Front. As a result of the Spring Offensive, Britain and France also pulled half of their divisions back to the Western Front.