In August 1431 Grand Master of the Teutonic Order Paul von Rusdorf decided to declare war and undertake a surprise attack on Poland. Many cities, castles, villages were destroyed and burned, and many people killed. On 2 September a truce was concluded to be kept until 24 June in 1433. In revenge for this aggression, in July 1432 a pact of assistance between Hussite Bohemia and Poland wad signed at Pabianice. ; In agreement with this pact, in 1433 the Hussites launched an expedition against the Teutonic Order. The "Orphans" army (Hussite party which adopted this name after death its "father" Jan Žižka) under the command of Jan Čapek, the total strength being reported between 5000 and 10000 men, was supported by Polish troops from Great Poland. A joint army crossed the border near the castle of Santok, surrendered to the Poles by the Knights of the Order of St John of Jerusalem. During this war the Teutonic Order was dependent on mercenary troops, and there were more than 2000 mercenaries in Neumark at the time. ; When combined armies of "Orphans" and Poles approached, they did not dare to fight in field battle, and were used only as garrisons defending cities. The first attack was launched against the strongly fortified city of Strzelce (Friedeberg), which was taken by surprise on June 7. Prussian and Polish chronicles recorded, that during this campaign the whole land of Neumark was destroyed and 12 cities were captured by the Hussites and Poles. According to the Grand Master, the mercenaries surrendered voluntarily the city of Dobiegniew (Woldenberg). ; It was not however, betrayal but consequence of the fact, that Teutonic Order was not able to pay salaries on time. In earlier studies, some of the Czech and Polish historians (e.g. Josef Macek) argued, that advance in Neumark was facilitated by many subjects of the Order supporting Hussite ideas. It should be strongly emphasized that there is no evidence in the sources, to confirm such a thesis.