Why do some military boots have steel nails on the soles?

British parade shoe used in the 50's, 60's, and 70’s notable for the metal "horse shoe" on the heel and the metal studding in the leather sole. These military boots are called “Ammunition boots"

Ammunition boots, also known as parade boots, drill boots. It is the standard shoe of the British Army from the late 1880s to the late 1950s. The British Army reverted to black leather ankle boots for non-commissioned personnel after the First World War. Constructed of leather with the smooth side outermost, from the 1930s they were fitted with protective toe caps of similar style to those used by earlier munitions workers - which may account for the reason why this style of boot became known as 'ammunition boots.' They replaced the ankle boots that served in the early 19th century and became the main force on the battlefield at the time.

Ammunition boots were unlined ankle-boots with leather laces, iron heel-plate and toe-plate, and iron-studded leather sole. The vamp (front) and quarters (sides) were often made of a contrasting type of leather than the toe case (toe cap) and counter (heel cap), one made of "pebble-grained" (dimpled) leather and the other of smooth leather. They were designed to be hard-wearing and long-lasting rather than comfortable. The hobnail-studded soles made a loud crunching sound when the wearer was marching, earning them the nickname "crunchies".

The most special ammunition boots are the metal "horse shoe" on the heel and the metal studding in the leather sole. Some of these shoes are made of leather soles, mostly office shoes. The role of steel nails is to reduce leather. The wear of the bottom also makes the footsteps of the officers walk sounder. These two office shoes are the shoes with iron on the soles, which have improved the lack of comfort in the past. They have a hard outsole while maximizing the internal comfort.

There is also a kind of "ammunition boots" is a high-top leather boots, we generally call it a parade boots, and now the parade boots are generally used for military parade wear, The boots were the focus of much drill and attention. Achieving a high polish was often the aim and required hours of "bulling" (vigorous polishing) until it achieved a deep sheen. The bright surface is matched with his loud footsteps, adding to the performance of the soldiers in the military parade.

This are the new two black ammunition boots launched in 2018: ankle boots, six eyelets, loose tongues, leather caps at the toe and heel, thick leather soles, metal horseshoes on the heel, and soles. Metal rivets. There is very hard leather on the upper.  The boots improve with Goodyear welt sole, thicker upper leather, heavier duty steel studs and laminated leather sole. They have excellent performance in the North African desert, Burma's jungle Normandy beaches.