In what ways was world war l truly global conflict

It started with Germany and Austria-Hungary along with Russia. But then the Ottoman Empire allied with Germany and Austria-Hungary. Then Germany sunk the Lusitania which then involved Britain, France, and the U. S. Then Italy and Bulgaria joined in hopes of gaining more new territory and power. Serbia was forced in when Germany and Austria-Hungary attacked them.

Meaning, everyone on the globe was involved. WWI affected everyone's lives.

WW1 involved a majority of the countries across the globe, beginning with the assassination of archduke Ferdinand. As smaller countries began to fight, larger powers like Germany and England and France began to get involved, as did America after the Zimmerman telegram.