The "O-Class" refers to a series of submarines used by the Royal Navy during World War II. These submarines were designed for coastal defense and were known for their relatively small size and agility. They typically displaced around 600 tons and were equipped with torpedoes and deck guns for engaging enemy vessels. The O-Class submarines played a crucial role in patrolling the waters around the British Isles and conducting reconnaissance missions. Their design allowed for effective operations in shallow waters, making them suitable for various naval tasks during the conflict.