The longest swords historically used in warfare are known as "greatswords" or "two-handed swords." These large weapons were designed to be wielded with two hands due to their substantial size and weight. The length of the longest swords can vary, but they typically measure around 150 to 180 centimeters (59 to 71 inches) in total length, with the blade accounting for a significant portion of that measurement.

Examples of long swords throughout history include:

1. Zweihänder: The Zweihänder, meaning "two-hander" in German, was a massive two-handed sword popular in the late medieval and Renaissance periods. It had an average length of approximately 150 to 180 centimeters (59 to 71 inches) overall, with the blade alone measuring around 110 to 150 centimeters (43 to 59 inches).
2. Claymore: The Scottish claymore was a large two-handed sword used in the late medieval and Renaissance eras. It had a similar length to the Zweihänder, with an overall length of around 140 to 160 centimeters (55 to 63 inches) and a blade length of about 100 to 130 centimeters (39 to 51 inches).
3. Ōdachi/Nodachi: The ōdachi or nodachi was a Japanese sword characterized by its long blade. While not as long as some greatswords from Europe, the ōdachi had an overall length ranging from approximately 150 to 200 centimeters (59 to 79 inches), with the blade measuring around 120 to 150 centimeters (47 to 59 inches).

These long swords were primarily used by skilled warriors in specialized combat situations or as ceremonial weapons. Due to their size, they often required significant strength and training to wield effectively.