"Under the White Ensign: A Naval Story of the Great War" by Percy F. Westerman is a historical novel likely written in the early 20th century. The book tells the story of the British armed merchant cruiser "Portchester Castle" during World War I, focusing on the adventures of its crew, particularly Sub-lieutenant Tom Webb, as they encounter dangers such as U-boats and espionage in the Mediterranean theater. The narrative captures the tension and camaraderie of naval warfare, making it suitable for readers interested in historical adventure tales. At the start of the novel, readers are introduced to Sub-lieutenant Tom Webb while he is on watch aboard the "Portchester Castle", navigating the treacherous waters of the Bay of Biscay. As the ship is on patrol for hostile submarines, Webb quickly proves his competence and becomes acquainted with Laddie, a sheepdog belonging to Lieutenant Jack Osborne. The calm quickly turns to chaos when Laddie barks at a lurking U-boat, prompting an immediate emergency response that showcases the urgency and unpredictability of naval warfare. The chapter culminates in an intense encounter with the submarine, setting the stage for further thrilling escapades in the Mediterranean. (This is an automatically generated summary.)