From Bvio

The question of "'''the largest naval battle in history'''" is controversial, and depends on the definition of battle and the criteria used to assess the size, such as personnel, the number of ships, their tonnage, the area involved, and the duration. There are two main candidates: * Battle of Ecnomus, 256 BC. In terms of number of ships involved, Ecnomus was largest with 680 ships. Ecnomus was also a single engagement where a large number of ships were fighting in a very small area. Some historians accept Roman claims that Rome had approximately 100,000 personnel. If this is true, it is probable that at least 200,000 Roman and Carthaginian sailors and soldiers were involved. * Battle of Leyte Gulf, 1944, the largest in terms of tonnage of ships and the area in which the action took place. It is estimated that about 200,000 personnel were involved. Leyte Gulf was also a major air battle. It encompassed several engagements over the space of three days, united by the strategies of the Allied and Japanese commanders.