The Nursery Rhyme, One misty, moisty, morning, talks of an "old man all clothed in leather". Although the origins of this Nursery Rhyme cannot be traced the subject of leather clothing is an interesting one and worthy of mention.

History of Leather Clothing
The hides of animals have been used for time immemorial by man in an effort to keep warm. The manufacture of making items of apparel leather dates back thousands of years. The father of William Shakespeare moved from farming the land and used the skins of animals to set up trade as as a Glover and Whittawer (making saddles, harnesses and fine leather gloves)

Medieval Knights, Armour and Leather Coats!
Yes, armour replaced leather coats originally but leather coats did eventually did replace armour! By the 1600's armour was in decline. It has been stated that this was due to the introduction of firearms but the force of arrows from the mighty longbows could also penetrate armour. The use of armour was of particular use to knights on horseback as protection from the lance, and the armour became so thick and heavy that it declined together with the use of the lance. By the English Civil War some men were still using the breastplate but the majority preferred the helmet. And they swapped the full armour for leather coats, which provided protection against the sword and bayonet. The helmet is all that remains in today's armies of the armour of the Medieval Knights!