In Northwestern Croatia, the beginning of the wars with the Ottoman Empire caused many problems but in the long term, it both reinforced the northern of the ruling Habsburgs. There was the modest influence of the Renaissance in styles of fortification. The plan for the fortified city of Karlovac in 1579 was the first radially built city in the Balkan Peninsula using the so-called "ideal city" plan like is found afterward in Renaissance and Baroque Europe (See Baroque). The Muslim Turk Ottomans were a constant threat from the South and East and hindered the over-all development of Serbo-Croatian expression in the region.