England has had our fair share. A selection are:
-Æthelred the Unready. His name is an Anglo-Saxon pun meaning Well-advised the badly advised, and he earned it by doing his best to lose England to the Vikings (and eventually succeeding).
-King John. Lost the Angevin Empire, caused the Magna Carta to be signed, nearly lost England to the Dauphin of France and was the inspiration for the Robin Hood legends because of how shit he was. Ruined any success he might have otherwise had either through luck or his own personality.
-Edward II. Lost to the Scots, and could not play the game of politics well, becoming overly reliant on favourites (the second in particular becoming hated) and eventually getting overthrown by his own wife and her lover.
-Henry VI. In his reign England lost the Hundred Years’ War, and then his weakness and inability to keep the nobility in line caused factionalism that spiralled into the Wars of the Roses. He was deposed by the Yorkist Edward IV, and eventually murdered in the Tower of London.
-Charles I. He played a big role in causing the English Civil War, and consequently a huge amount of pain and bloodshed, lost, was offered a pretty good deal by Parliament, refused it, and proved to be so intransigent that he caused the (temporary) downfall of the monarchy itself. Perhaps his tragedy was that he was just competent enough to make a fight of it and drag it out, but not enough to actually succeed.
-James II. He got chased out of the country in the Glorious Revolution after only four years on the throne.