Cavalry (from French cavalerie, cf. cheval ‘horse’) or horsemen were soldiers or warriors who fought mounted on horseback. The Cavalry was historically the most mobile of the combat arms. An individual soldier in the cavalry is known by a number of designations such as cavalryman, horseman, dragoon and many more…
The time gap between the medieval cavalry and the first world war cavalry is quite substantial so there are a lot of differences between them
Medieval knights also charged with lances but never swords, they wore heavy armor, and generally did not dismount in combat. They always had a shield, charged in deep lines up to ten horses deep, and lacked missile weapons because firearms were not very developed back then. They never did scout work, modern cavalry all did scouting. Medieval knights had at least nominal chivalry to follow, meaning no massed charges into the rear of an enemy.
During the European Middle Ages, there were three primary types of war horses: The destrier, the courser, and the rouncey, which differed in size and usage. A generic word used to describe medieval war horses was charger. On the battleground, medieval cavalry played decisive roles with its use of tactics. The light cavalry played important role in scouting, skirmishing, and performing outpost duties while heavy medieval cavalry used tactics of using lances and ranged weapons during the main battle.
First World War Cavalry
The cavalry forces of the First World War were a lot more sophisticated and way less armored. They used lances and sabers but wore no armor. Some were equipped with carbines and pistols for firing from horseback, and they charged in lines that were generally shallow, two to three horses deep. Modern cavalry would very often use flanks and other dishonorable practices.
In the very early days of World War One, cavalry was a devastating weapon when used against infantry. A British cavalry charge at the Battle of Mons was enough to hold off the advancing Germans. However, with the coming of static trench warfare, the use of cavalry became rare. Barbed wire, mud and machine guns were a deadly combination for any cavalry soldier. Horses became beasts of burden as opposed to having any strategic impact on the Western Front in terms of their use in cavalry attacks.