Not only the Pashas (governors) of Trabzon until the 19th century, but real authority in many of the "cazas" (districts) of each sanjak by the mid-17th century lay in the hands of relatively independent native Laz derebeys ("valley-lords"), or feudal chiefs who exercised absolute authority in their own districts, carried on petty warfare with each other, did not owe allegiance to a superior and never paid contributions to the sultan. In the period following the war of 1828–1829, Sultan Mahmud II attempted to break the power of the great independent derebeys of Lazistan. In the event, the Laz derebeys, led by Tahir Ağa Tuzcuoğlu of Rize, did rise in revolt in 1832. The revolt was initially successful: at its height in January 1833, but by the spring of 1834, the rising had been put down. The suppression of the rising had finally broken the power of the Laz derebeys. This state of insubordination was not really broken until the assertion of Ottoman authority during the reforms of the Osman Pasha in the 1850s.