The main, or central, idea of the passage is A Polish army unit grew so fond of a pet bear that they enlisted the animal in the army in order to bring him aboard a military ship. How does the detail in bold develop the main idea?
While traveling through Iran during World War II, a group of Polish soldiers encountered a young boy with an intriguing possession available for trade: a bear cub. The soldiers promptly bought the cub, named him Wojtek, and took him to join the rest of their unit. The playful bear adapted well to military life. However, when the unit was sailing for Italy, officials refused to allow the bear on the ship, saying that only soldiers were permitted. The solution was both obvious and extraordinary: the soldiers arranged for Wojtek to be officially enlisted in the army. As an enlisted soldier, he could accompany the men on their mission. "He didn't receive money," recalled one former soldier in an interview with the BBC World Service, "but was officially a Polish soldier." Wojtek remained with the company throughout the war and even helped carry heavy crates of ammunition to soldiers on the battlefield.