How Close Did German Submarines Get to Portland Harbor in WWII? If you've ever been to Fort Williams in Cape Elizabeth or to Peaks Island, you've seen the remnants of gun batteries and lookout towers. These were used in WW1 and especially in WW2 to protect Portland Harbor. You may think that World War II was fought far away from Maine, so you may be surprised how close those nasty Nazis really got. How Busy Was Portland Harbor in World War II? The harbor was a hotbed of activity! The South Portland shipyards built over 235 Liberty ships between 1941 and 1945. That's like 5 ships a MONTH. Thousands of Navy men were trained on Casco Bay Islands and the harbor was an important refueling spot. Portland Harbor was