How the war started?

Answer 1

There have been many wars, and they have started in a variety of ways, although certain general patterns can be observed. When two nations are in competition, seeking to control the same territory, or to exploit the same resources, or to promote their own religions, and so forth, and either or both of them are too selfish to agree on a reasonable compromise, the result will be violence. And even a small amount of violence, such as the murder of a single person, can easily lead to reprisal and larger conflict, resulting in war. WW I is thought to have begun with the assassination of a single person, the Archduke Franz Ferdinand.

Answer 2

it started at the age of 1