The answer is prior to 1942, the US pursued a defensive war in the pacific. This strategy failed, so, the US adopted the "island-hopping" strategy to overwhelm Japanese forces on islands. The battle that forced this new form of thinking was the Battle of Midway, in which the US began a counter-offensive campaign against Japan.
C.
About 1,615,000 people living in the United States in 1910 were born in Ireland.
