or Muslim enemies. The Almogavars originally fought for the counts of Barcelona and kings of Aragon, but as the Catalan Company, they followed Roger de Flor in the service of the Byzantine Empire. In 1311, the Catalan Great Company defeated at the Battle of Halmyros their former employer, Walter V, Count of Brienne, after he refused to pay them, and took over the Duchy of Athens. The Great Company ruled much of central and southern Greece until 1388–1390 when a rival mercenary company, the Navarrese Company were hired to oust them. Catalan and German mercenaries also had prominent role in the Serbian victory over Bulgarians in the Battle of Velbuzd in 1330. During the later Middle Ages, Free Companies (or Free Lances) were formed, consisting of companies of mercenary troops. Nation-states lacked the funds needed to maintain standing forces, so they tended to hire free companies to serve in their armies during wartime. Such companies typically formed at the ends of periods of conflict, when men-at-arms were no longer needed by their respective governments. The veteran soldiers thus looked for other forms of employment, often becoming mercenaries. Free Companies would often specialize in forms of combat that required longer periods of training that was not available in the form of a mobilized militia. The formed a distinctive subculture in medieval France who alternated between serving as mercenaries in wartime and bandits in peacetime. The were very destructive and became a significant social problem. After the Treaty of Brétigny ended the war between England and France in 1360, the French countryside was overrun by Free Companies of while the French Crown lacked the necessary military and economic strength to put an end to their activities. To rid France of the rampaging mercenaries and to overthrow the pro-English King Pedro the Cruel of Castile, Marshal Bertrand du Guesclin was directed by King Charles V of France to take the Free Companies into Castile with the orders to put the pro-French Enrique de Trastámara on the Castilian throne. Guesclin's mercanaries were organized into the Big Companies and French Companies and placed a decisive role in putting Enrique on the Castilian throne in 1369, who styled himself King Enrique II, the first Castilian monarch of the House of Trastámara. The White Company commanded by Sir John Hawkwood is the best known English Free Company of the 14th century. Between the 13th and 17th centuries