The Walls of Hell - Jock Mahoney, Fernando Poe Jr., 1964

https://www.imdb.com/title/tt0058235/ This gritty, atmospheric war movie dramatizes a chapter of World War II history in which 10,000 Japanese soldiers, fearing execution if they surrendered, disobeyed their own superiors' orders and barricaded themselves in Manila's Intramuros section along with a thousand or so unfortunate civilians. The walled city-within-the-city was built by Spanish colonialists from 1590 onward.