The people on the island of Curaçao feared for their safety because, in February 1942, German U-boats torpedoed a large oil refinery on the island of Aruba, just next to Curaçao, as explained in the opening chapter of Theodore Taylor's The Cay. Germans targeted the Caribbean islands because the islands produced the largest oil refineries in the world, such as the Royal Dutch Shell on Curacao, which Phillip's father works for. Many important parts of the world relied on the oil refineries for oil, including Great Britain, the US, and Africa. If the Germans were able to successfully cut off oil supply, then allied forces would be significantly impeded.
Though only Aruba is hit in the opening chapter of the story, as events progress, people on Curaçao grow more concerned. As Phillip's father informs him, the island of Curaçao has no weapons to fend off the Germans. Immediately after the bombing, ships in the harbor came to a standstill because they are too afraid to move. Ships are relied upon for fresh drinking water, fruits, and vegetables. When supplies begin running low, the people of Curaçao begin panicking even more, especially Phillip's mother, who wants to return to America. They are most struck with fear when a tanker is torpedoed just off the coast of Curacao; the tanker had been headed for Curaçao's capital city, Willemstad.