Yankee Doodle was written by an English surgeon in the 1750s to poke fun at the “hick” colonists. In England at the time, “Macaroni” was a nickname for young British men who dressed in very flamboyant Italian style – sticking a single feather in your cap definitely didn’t make you a Macaroni. The colonists took to the song anyway, and Geo. Washington had it played as the English General Cornwallis surrendered.
Yankee Doodle Boy was written by George M Cohan for his Broadway musical. His parents were from West Cork, Ireland (original spelling Keohane). He also wrote You’re a Grand Old Flag, Give My Regards to Broadway, and Over There among hundreds of others.
God Bless America was written in 1918 by Russian Jewish Immigrant Irving Berlin. It got cut from his show, he revived it later for Kate Smith. He also donated most of the royalties to the Boy Scouts, Girl Scouts, and Campfire Girls.