In May 1915, the German navy's fleet consisted of just thirty U-boats, which limited their reach and effectiveness. However, by 1917, the number of U-boats had dramatically increased to over one hundred. This significant expansion was marked not only by quantity but also by advancements in technology, with many U-boats being larger and more powerful than the earlier models. These improvements allowed for greater firepower, as the new U-boats were designed to carry more torpedoes.

This transformation of the U-boat fleet highlights the evolving nature of naval warfare during World War I. The escalation from a modest number of submarines to a formidable fleet underscored the shift in tactics and the increasing threat posed to Allied shipping lines. Erik Larson's "Dead Wake" illustrates this pivotal moment in naval history, showcasing how these advancements contributed to the eventual challenges faced by ships like the Lusitania.