There were at least three wars in the world that could be said to have started in 1741. Of these, the most famous to Westerners, at least, is the War of the Austrian Succession.
There was a war in 1741 in Java between Dutch colonialists and a combined force of Javanese and Chinese. There was a war that began in 1741 between Russia and Sweden (along with some Finns). However, the biggest war was the War of the Austrian Succession. This was a war that was ostensibly over whether Maria Theresa could become the ruler of Austria after her father, Charles VI, died. But the war was really about the desire of the Prussians and the French to reduce the power of Austria.