The cavalry were originally soldiers who traveled and fought on horseback, usually with swords or lances. There were two main types of cavalry:
- Light cavalry, lightly armed soldiers on small fast horses, which was responsible for seeking out and harassing the enemy; and
- Heavy cavalry, more heavily armoured soldiers, often wearing armour, on larger and more powerful horses.
Heavy cavalry were used as "shock" troops to attack infantry formations and other cavalry.
Although not strictly cavalry, the Australian Light Horse units of the First World War can be loosely classified as such. They used horses to move quickly and were organised in the same way as cavalry units, but actually did their fighting dismounted as infantry soldiers. Although some light horse units were issued with swords late in the war, their main weapon was the rifle and bayonet. With the mobility provided by their horses, they were well suited to the reconnaissance roles for which light cavalry had traditionally been used.