A robber baron or robber knight (German: Raubritter) was an unscrupulous feudal landowner who, protected by his fief's legal status, imposed high taxes and tolls out of keeping with the norm without authorization by some higher authority. Some resorted to actual banditry. The German term for robber barons, Raubritter (robber knights) was coined by Friedrich Bottschalk in 1810.
Some robber barons violated the custom under which tolls were collected on the Rhine either by charging higher tolls than the standard or by operating without authority from the Holy Roman Emperor altogether. During the period in the history of the Holy Roman Empire known as the Great Interregnum (1250-1273), the number of such tolling stations exploded in the absence of Imperial authority.
Medieval robber barons most often imposed high or unauthorized tolls on rivers or roads passing through their territory. Some robbed merchants, land travelers, and river traffic--seizing money, cargoes, entire ships, or engaged in kidnapping for ransom.
Tolls were collected from ships sailing on the River Rhine in Europe for one thousand years from around 800 AD to 1800 AD. During this time, various feudal lords (among them archbishops who held fiefs from the Holy Roman Emperor) collected tolls from passing cargo ships to bolster their finances. Only the Holy Roman Emperor could authorise the collection of such tolls. Allowing the nobility and Church to collect tolls from the busy traffic on the Rhine seems to have been an attractive alternative to other means of taxation and funding of government functions.
The Holy Roman Emperor and the various noblemen and archbishops who were authorised to levy tolls seem to have worked out an informal way[vague] of regulating this process. Among the decisions involved in managing the collection of tolls on the Rhine were how many toll stations to have, where they should be built, how high the tolls should be, and the advantages/disadvantages. While this decision process was made no less complex by being informal, common factors included the local power structure (archbishops and nobles being the most likely recipients of a charter to collect tolls), space between toll stations (authorized toll stations seem to have been at least five kilometres apart), and ability to be defended from attack (some castles through which tolls were collected were tactically useful until the French invaded in 1689 and levelled them). Tolls were standardized either in terms of an amount of silver coin allowed to be charged or an "in-kind" toll of cargo from the ship.
The men who came to be known as robber barons or robber knights (German: Raubritter) violated the structure under which tolls were collected on the Rhine either by charging higher tolls than the standard or by operating without authority from the Holy Roman Emperor altogether.
Writers of the period referred to these practices as "unjust tolls," and not only did the robber barons thereby violate the prerogatives of the Holy Roman Emperor, they also went outside of the society's behavioural norms, since merchants were bound both by law and religious custom to charge a "just price" for their wares.
During the period in the history of the Holy Roman Empire known as the Great Interregnum (1250-1273), when there was no Emperor, the number of tolling stations exploded in the absence of imperial authority. In addition, robber barons began to earn their opprobrium by robbing ships of their cargoes, stealing entire ships, and even kidnapping.
In response to this organized, military lawlessness, the "Rheinischer Bund," or Rhine League was formed by 100 Cities, and from several princes and prince-prelates (lords of the Church), all of whom held large stakes in the restoration of law and order to the Rhine.
Officially launched in 1254, the Rhine League wasted no time putting robber barons out of business by the simple expedient of taking and destroying their castles. In the next three years, four robber barons were targeted and between ten and twelve robber castles destroyed or inactivated.
The Rhine League was not only successful in suppressing illicit collection of tolls and river robbery, they also took action against other state aggression. For example, they are documented as having intervened to rescue a victim of abduction by the Baron of Rietberg.
The procedure pioneered by the Rhine League for dealing with robber barons - to besiege, capture and destroy their castles - survived long after the League self-destructed from political strife over the election of a new Emperor and military reversals against unusually strong robber barons.
When the Interregnum ended, the new king Rudolf of Habsburg applied the lessons learned by the Rhine League to the destruction of the highway robbers at Sooneck, torching their castles and hanging them. While robber barony never entirely ceased, especially during the Hundred Years' War, the excesses of their heyday during the Interregnum never recurred.
The reign of King Stephen of England (1096-1154) was a long period of civil unrest commonly known as "The Anarchy". In the absence of strong central kingship, the nobility of England were a law unto themselves, as characterised in this excerpt from the Anglo-Saxon Chronicle:
When the traitors saw that Stephen was a mild good humoured man who inflicted no punishment, then they committed all manner of horrible crimes. They had done him homage and sworn oaths of fealty to him, but not one of their oaths was kept. They were all forsworn and their oaths broken. For every great man built him castles and held them against the king; they sorely burdened the unhappy people of the country with forced labour on the castles; and when the castles were built they filled them with devils and wicked men. By night and by day they seized those they believed to have any wealth, whether they were men or women; and in order to get their gold or silver, they put them into prison and tortured them with unspeakable tortures, for never were martyrs tortured as they were. They hung them up by the feet and smoked them with foul smoke. They strung them up by the thumbs, or by the head, and hung coats of mail on their feet. They tied knotted cords round their heads and twisted it until it entered the brain. They put them in dungeons wherein were adders and snakes and toads and so destroyed them. Many thousands they starved to death.
Michael Heller refers to the original robber barons to illustrate his tragedy of the anticommons in his 2008 book. The tragedy of the anticommons is a type of coordination breakdown, in which a single resource has numerous rightsholders who prevent others from using it, frustrating what would be a socially desirable outcome.