Though America’s entry into World War I was pivotal, the decision didn’t come easy – especially with a third of America’s population at the time of Irish and German descent.

During America’s neutrality (1914-1917) there was a sharp divide of opinion pertaining to intervention. Though many supported war against the Germans, it meant an alliance with Britain. And with a large Irish population came fervent anti-British views, so most Irish descendants were invested in American neutrality.

Irish Americans picketed in front of the White House to protest US support for Britain during the war, said war expert Joseph V. Micallef in a recent piece for the Huffington Post.

There were further White House protests shortly after the war for US failure to support Ireland against the British, with signs that read, “Lloyd George the Anarchist, and Wilson his Junior partner” or “Uncle Sam! Can you watch John Bull murder ‘the poor old woman?’”

Micallef wrote: “The United States, long a hot bed of Irish nationalism and an important source of its funding, had a significant Irish-American population with pronounced anti-British views.

“An equally large German-American community, while not specifically anti-British, was certainly pro-German in its views, and at the very least, was a strong proponent of American neutrality.”

A significant number of American volunteers fought with the British and French armies during US neutrality – but less publicized was the number of Irish and German American volunteers who fought with Germany, said Micallef.

“There was an Irish Battalion that fought with the Imperial German Army during the war comprised of both native Irishman and Irish-Americans,” he wrote.

The number of American citizens fighting for the Germans was low compared to those volunteering against, but it was still a considerable amount.

However, Micallef said, “As the war progressed, the German government's policy of unrestricted submarine warfare and the resultant loss of American lives; its diplomatic machinations in Mexico to create an anti-United States, German-Mexican alliance; and a Berlin directed campaign of sabotage against U.S. factories and port facilities, caused American public opinion to tip increasingly in favor of the British and French and paved the way for America's eventual entry into the conflict.”

US entry meant a huge amount of added industrial power, smoother munitions trade to Europe, the full faith of the stable US government, and most importantly millions of new recruits and a powerful Navy, all of which were imperative in winning the war.