Overview: At Villers-Bretonneux, German and British tanks clash marking the first tank-on-tank battle in history. In the same week, the most successful flying ace of World War 1 is shot down over France: Manfred von Richthofen dies after scoring 80 victories. Meanwhile, the British Navy attempts to eliminate the German U-Boat threat with a daring raid on Zeebrugge and Ostende.