Fascinating footage has surfaced showing American cavalry preparing for service in the First World War.

Video from 1917 shows horses forming up as their riders practice mounting and dismounting in unison, charging the enemy and moving over rough terrain.

Cavalry units were viewed as an essential attacking weapon at the start of the war and used extensively by all forces, though by the time America joined in April 1917 they were fast being replaced by tanks.

Fascinating footage has emerged showing American cavalry units being trained in 1917, ready for deployment during the First World War

One of the last cavalry charges of the war happened at the Battle of Moreuil Wood on March 30, 1918, six months before armistice.

Canadian cavalry charged at German positions, managing to defeat a superior force despite the fact that they were supported by machine guns.

But while the battle was technically a victory, three-quarters of the mounted units involved were killed.

The charge at Moreuil Wood was an execption rather than the rule at this point in the conflict, however.

Because of their vulnerability to modern weapons, and a shortage of replacements, horses were largely put to work away from the battlefield.

Instead, the animals were used to haul heavy weapons, ammunition, and equipment over muddied ground pock-marked with shell holes that early vehicles struggled to cope with.

Riders and mounts can be seen forming up, cantering over rough terrain and practicing charging the enemy in the black and white footage

America used horses to attack for only a short time as powerful artillery, and the invention of machine guns and tanks, had severely limited their effectiveness

They were also used to carry messengers and as scouts because they moved faster over rough ground.

All major combatants during the First World War deployed cavalry at some point, with Britain and Canada keeping them in offensive roles the longest.

America only used them in combat for a short period, before a lack of replacements forced them off the battlefield.

While exact numbers are not known, hundreds of thousands of the animals died during the war from bullet or shrapnel wounds.

Even after they stopped being used in combat many died from disease and starvation as fodder became scarce.