Question

in which year the first and second world war happens

Answer 1

The two dates most often mentioned as “the beginning of World War II” are July 7, 1937, when the “Marco Polo Bridge Incident” led to a prolonged war between Japan and China, and September 1, 1939, when Germany invaded Poland, which led Britain and France to declare war on Hitler's Nazi state in retaliation.

Answer 2

First world war happens from 28 July 1914 to 11 November 1918
second world war happens from 1 September 1939 to 2 September 1945