After the rapid German victory in Poland, a period in what became known as the phony war began. For a short period the war in Europe lost some of its urgency, although Roosevelt did his best to allow the allies to purchase as much war material as they could. Suddenly, on May 10th, the Germans launched a full scale attack on the west. The Netherlands and Belgium were quickly overrun. It soon became apparent that the French were doomed. Roosevelt immediately asked for the most massive arms buildup in American history. At the same time, he continued to give all possible aid to the British. He used the limited diplomatic leverage at his disposal to try to keep Italy out of the fight, but once it became clear that the French were totally defeated, the Italians attacked. The remaining question was whether Britain would manage to stand alone. Winston Churchill became Prime Minister of Britain. Churchill's strong attitude more than anything else, helped convince the President that Britain would stand.