The QF 2-pounder, officially known as the 40 mm gun, was a British anti-tank and naval artillery piece developed in the 1930s. It was designed to fire a 2-pound (0.91 kg) projectile and was widely used during World War II. The gun was mounted on various platforms, including tanks, ships, and towed artillery, making it versatile for different combat scenarios. This weapon played a significant role in early tank battles, particularly against German armor. Its effectiveness diminished as enemy tanks became better armored, leading to the development of more powerful artillery. The QF 2-pounder was eventually replaced by more advanced systems, such as the QF 6-pounder.