What was the war of currents of thomas Edison and Nikola Tesla?

Tesla and Edison became involved with this issue since Edison was working in the monopoly of the electric system based on his direct current system. Using direct current to light houses is more costly and dangerous that using alternant current. So, Tesla won the war.

If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found the object of his search. ... I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.

• New York Times (19 October 1931)