Diwanus was the leader (capitaneus) of Bartians

Bartians

The Bartians were an Old Prussian tribe who were among the last pagans of Europe before the Northern Crusades forced their conversion to Christianity...

, one of the Prussian clans

Old Prussians

The Old Prussians or Baltic Prussians were an ethnic group, autochthonous Baltic tribes that inhabited Prussia, the lands of the southeastern Baltic Sea in the area around the Vistula and Curonian Lagoons...

, during the Great Prussian Uprising (1260–1274) against the Teutonic Knights

Teutonic Knights

The Order of Brothers of the German House of Saint Mary in Jerusalem , commonly the Teutonic Order , is a German medieval military order, in modern times a purely religious Catholic order...

. He was son of Kleckis (Old Prussian: bear) and therefore is sometimes referred to by a nickname derived from the word bear. His first major victory came when Schippenbeil

Sepopol

Sępopol is a town in Bartoszyce County, Warmian-Masurian Voivodeship, Poland, with 2,025 inhabitants ....

 fell in 1263 after almost three years of siege. Twenty knights and their men sallied out to fight the joint forces of Batians and Sudovians in an open battle. However, the pagans blocked escape routes and all Teutons were killed. In terms of knights killed, it was one of the top ten losses by the Teutonic Knights during the 13th century. The garrison at Schippenbeil was left with too few soldiers and supplies to withstand the siege and escaped through Galindia to Masovia. Diwanus expected that fugitives would take a shorter route north to Balga

Balga

Balga was a medieval castle of the Teutonic Knights. Its ruins are in the Pogranichny municipality, Bagrationovsky District in Kaliningrad Oblast, Russia; located on the shore of the Vistula Lagoon north of Mamonovo, about southwest of Kaliningrad....

 or Königsberg

Königsberg

Königsberg was the capital of East Prussia from the Late Middle Ages until 1945 as well as the northernmost and easternmost German city with 286,666 inhabitants . Due to the multicultural society in and around the city, there are several local names for it...

, therefore the knights had a head start

Head start (positioning)

In positioning, a head start is a start in advance of the starting position of others in competition, or simply toward the finish line or desired outcome...

. Diwanus soon learned about the true route and, with a handful of his best men, hurried to pursue the fugitives. During a charge on the escapees, Bartians killed three knights, but Diwanus was seriously injured.

Since all major Teutonic castles in Bartia fell, Bartians did not have the need to safeguard their land from potential attacks from Teutonic strongholds. They were free to send men to help other Prussian clans. Diwanus and his men were making minor expeditions into Pogesania and Chełmno Land

Chełmno Land

Chełmno land or Chełmno region is a historical region of Poland, located in central Poland, bounded by the Vistula and Drwęca rivers....

. In 1271 a major campaign was organized together with Pogesanian leader Linko. The Bartian infantry and Pogesanians besieged a border castle, but were fended off by the Knights from Christburg

Dzierzgon

Dzierzgoń is a town in the Pomeranian Voivodeship in Poland. It is located in Sztum County east of Malbork and south of Elbląg on the river Dzierzgoń...

. The Prussians, who managed to escape, joined their cavalry while the Knights set up their camp on the opposite bank of the Dzierzgoń River

Dzierzgon River

The Dzierzgoń is a river in Northern Poland.It starts west of Morąg in the Warmia-Masuria Voivodeship and empties into Lake Drużno south of Elbląg.The town of Dzierzgoń lies on the river....

, blocking the route home. When Christians retired for the night, one half of the Prussian army crossed the river in a distance, in order to attack the Knights from the rear, while the other half charged straight across the river. The Knights were encircled. The Battle of Paganstin saw twelve knights and 500 men killed. The Prussians immediately assaulted Christburg and almost captured it. The Prussians were still looting the surrounding area when cavalry from Elbing

Elblag

Elbląg is a city in northern Poland with 127,892 inhabitants . It is the capital of Elbląg County and has been assigned to the Warmian-Masurian Voivodeship since 1999. Before then it was the capital of Elbląg Voivodeship and a county seat in Gdańsk Voivodeship...

 arrived. Many of the Prussian infantry perished while cavalry escaped. Despite these losses, Diwanus was soon back and blocked roads leading to Christburg hoping to starve the castle. Three times the Knights tried to send supplies to the castle via the Dzierzgoń River, and each time the vessels were intercepted by the Bartians. However, Christburg refused to surrender.

In 1273 Diwanus brought 800 men for a siege on Schönsee

Wabrzezno

Wąbrzeźno is a town in Poland, in the Kuyavian-Pomeranian Voivodeship, about 35 km northeast of Toruń. It is the capital of the Wąbrzeźno County...

. The small outpost had only three knights and a handful of sergeants. Diwanus tried to persuade them to surrender, but they refused and tried to hide their true strength by dressing every soldier as a noble knight. When Bartians attacked, brother Arnold shot and killed Diwanus. The Bartians, left without a leader, returned home. They withdrew from the uprising, and within a year the war was lost.