The navy paved the way to the mainland of Japan by destroying japans naval force. This allowed marines and air force to keep pouring into Japans territories. The us army was part of the Air Force at the time so they provided air support as well as bombing runs on Japanese territories as well as establishing supply chains and helping fight alongside marines.
After the assassination of the archduke of Austria-Hungary. one country wanted to go to war with the other.
pulling the forced alliances with other countries into the conflict.
other events such as the sinking of the Lithuania, caused America and more of its allies to join the fighting also
