The longsword is a European sword used during the medieval and Renaissance eras. Longswords are also sometimes called bastard swords, greatswords or hand-and-a-half swords. The Scottish claymore is sometimes referred to as a longsword. The longsword was developed because plate armor replaced chainmail, so a longer and heavier sword was needed to penetrate the armor. The longsword is usually held in both hands although sometimes it may be used single-handed. This sword is used for striking, cutting and thrusting. This sword was not used as often in medieval combat as the lighter swords were much easier to handle.
The longest of these swords was the zweihander whose length was up to 6 feet. This sword was used by the landsknechts who came from the Holy Roman Empire or an area that is now modern-day Germany. These swords were also used to break up infantry formations by attacking pikes and halberds. Today the longsword is the most popular weapon used by European martial artists. If you are interested in obtaining further information on medieval martial arts, I suggest that you visit the Tinker Swords website. Michael Tinker Smith has also published a book which has a very thorough description of medieval swords. You can download this book from this website.