Convoy is a group of vehicles traveling together for defense against attack. At sea, one or more warships may protect a merchant ship convoy. During World War I (1914-1918) and World War II (1939-1945), most United States and British merchant ships crossing the Atlantic Ocean traveled in convoys. The convoys protected the ships chiefly from attacks by German submarines. The United States built many specialized ships for convoy duty and antisubmarine operations. The largest were warships known as destroyer escorts and aircraft carriers called escort carriers (see Destroyer ). Britain and Canada used warships called frigates and corvettes (see Warship (Frigates) ). During the Afghanistan War (2001-2021) and the Iraq War (2003 – 2011), many vehicle convoys were targeted by roadside bombs called improvised explosive devices (IED’s) .
