Looking for "sperm shaped island" I found the answer:
"Corregidor Island" is a significant islet with high hills located at the entrance of Manila Bay in southwestern Luzon Island in the Philippines.
During World War II, Corregidor was the site of two costly sieges and pitched battles - the first during the first several months of 1942, and the second in January 1945 - between the Imperial Japanese Army and the U.S. Army, along with its smaller subsidiary force at that time, the Philippine Army. Since the Japanese Army had invaded Luzon from the north (at Lingayen Gulf) in early 1942 and attacked Manila from its landward side, the American and Filipino troops there under the command of General Douglas MacArthur (with the only significant defensive army in the Philippines) retreated first into the defensible Bataan Peninsula west of Manila Bay. Then, when the army on Bataan was forced to surrender due to the lack of food and ammunition, Corregidor and its adjacent islets at Manila Bay were the final bastions to hold out against the Japanese Army - rather than being the first line of defense of Manila from a seaborne attack from the south. The American and Filipino soldiers on Corregidor and the islets then held out against the Japanese for as long as possible in order to deny to the Japanese Empire the use of Manila Bay as long as they could, but the Japanese Army brought heavy artillery to the southern end of Bataan, and proceeded to blockade Corregidor from any sources of food and fresh water.