The rapid growth of Istanbul coincided with the spectacular expansion of the empire. By the end of the sixteenth century Ottoman rule extended from Hungary to Yemen and from Algeria to Iraq. The warfare and statecraft of this imperial system were directed from Istanbul. The main Ottoman army marched out of the capital on endless military campaigns. Such was its ambitious reach that it twice laid siege to Vienna in the heart of Europe (1529 and 1683). The Ottoman fleet patrolled the Black Sea and the Mediterranean; in 1543 its ships even attacked the port of Toulon in France. European powers had permanent ambassadors stationed in Istanbul to conduct diplomatic negotiations and observe developments in the empire.