Definition:

Caliga was a heavy shoe studded with hobnails and worn by the ordinary roman soldier. Soldiers wearing the caliga -- i.e., the ordinary soldiers -- were known as caligati. Germanicus -- great nephew of the first emperor, Augustus, and adopted son of the second, Tiberius, put the caliga on his young son Gaius when they were among the soldiers. As a result, Gaius was named "little boots," and became the emperor Caligula.

Many of higher rank wore the calceus. Caliga could be used as metonomy for a common soldier.

See: Roman Sandals and Other Footwear