A jackboot is a military boot such as the cavalry jackboot or the hobnailed jackboot. Caligae (singular "") were heavy-duty, thick-soled openwork boots, with hobnailed soles. The hobnailed jackboot has a different design and function than the first type. He was in a full army outfit including the legionary hobnailed boots ("caligae"). In Mediterranean climates, soldiers typically wore hobnailed "open boots" ("caligae"). Outdoor shoes were often hobnailed for grip and durability.