the 1526 Turkish invasion as the Hungarians were no longer a politically united people. The resulting degradation of order paved the way for Ottoman pre-eminence. Jagiellonian-Habsburg attempt to organize defence against the Ottomans King Louis II of Hungary married Mary of Habsburg in 1522. The Ottomans saw this Jagiellonian-Habsburg marital alliance as a threat to their power in the Balkans and worked to break it. After Suleiman I came to power in Constantinople in 1520, the High Porte made the Hungarians at least one and possibly two offers of peace. For unclear reasons, Louis refused. It is possible that Louis was well aware of Hungary's situation (especially after the Ottomans defeated Persia in the Battle of Chaldiran (1514) and the Polish-Ottoman peace from 1525) and believed that war was a better option than peace. Even in peacetime, the Ottomans raided Hungarian lands and conquered small territories (with border castles), but a final battle still offered Louis a glimmer of hope. Accordingly, another Ottoman–Hungarian war ensued, and in June 1526 an Ottoman expedition advanced up the Danube. In the early 1500s, Vladislav II (ruled 1490–1516), Louis II and Croatian nobles repeatedly asked Holy Roman Emperor Maximilian I for help, but during Maximilian's reign, assistance for Hungary remained a plan. After the first chain of fortresses fell however, assessing the threat to his own provinces, Archduke Ferdinand (later Holy Roman Emperor Ferdinand I) made a significant effort to help his brother-in-law. When Nándorfehérvár was being sieged, he summoned his estates and proposed sending troops to Hungary. In the end, 2,000 German infantry troops were sent. From 1522 to the 1526 defeat at Mohács, field troops from Austria frequently arrived but were not placed into fortresses at the border as regular garrisons yet. Even though this military aid purportedly strengthened this area of the border, it had the undesired effect of dissolving the unified leadership that the ban had held until that time. Alfred Kohler opines that the coordination effort attempted by Ferdinand, Mary and Louis failed because the young Hungarian king showed a lack of vigour, which was also recognized by Hungarian nobles. Mary, on the other hand, was much more decisive and vigorous, but the non-Hungarian advisors she relied on created distrust. European events, and the Franco-Ottoman alliance In Europe, especially in Germany, negative trends have started to unfold. The Fuggers, who had taken control of the finances, "by around 1503