It's sometimes easy to forget that World War II wasn't originally a world war and that many countries hoped to let continental Europe fight it out against each other (including the United States). Some countries held on to hopes of remaining neutral and passed strict laws to prevent their people from joining the fight.
For those who wanted to take the fight to the Nazis, this was a bit of a problem. A few dozen U.S. pilots defied neutrality laws to join the Royal Air Force while some American soldiers like Lewis Millet ran away to join the Canadian Army.
For Irish soldiers, approximately 4,500 of them, the best option was to run away from the Emerald Isles and join the British Army. Irish Brigades had served well in other conflicts including World War I, the Mexican-American War (against the U.S), and the American Civil War (on behalf of the Union).
The men were grouped into the 38th (Irish) Infantry Brigade which was formed at the request of Prime Minister Winston Churchill. The 38th was commanded by Brig. Morgan John Winthrop O'Donovan.
O'Donovan was a World War I veteran who received the Military Cross for bravery. He led the 38th Brigade from soon after its formation in early 1942 to July of that year, overseeing the initial training and preparations to ship out to North Africa.
O'Donovan was later replaced by Brigadier Nelson Russell, another World War I veteran and holder of the Military Cross. Russell got his for leading a daytime raid of an enemy trench as a 19-year-old lieutenant. He was also known for a stint playing cricket for Ireland.
Under Russell, the 38th Irish Brigade was sent to the invasion of French North Africa. After suffering a bomb attack by the Luftwaffe as they were getting off of their ships, the Irish Brigade fought its way through Africa alongside the British and American forces. The Irish were deployed into the mountains around Tunis during the battle for the capital.
When the Allies made it into the city, the Irish Brigade was the first to march through the streets. After the celebrations at Tunis, the 38th was sent with other victorious units to prepare for the landings at Sicily in Operation Husky.
The Allies landed on Jul. 9, 1943. The 38th's major objective was a small village at the center of the Axis defenses in the Sicilian mountains. They made it to the objective and, on Aug. 3, began their assault against it. In a single night of fighting, they pushed the Axis our of the village and away from the ridgeline. They continued to push forward, helping other Allied soldiers capture and kill Axis forces.
On Aug. 17, after just over 5 weeks of fighting, the Axis had been pushed off the island and forced to return to Italy.
The Irish Brigade was then sent to take part in the invasion of Italy, a task which would occupy them for the rest of the war. They came ashore just a few days after the initial landings and then began pushing the Germans north past one defensive line after another. By this time, the Italian Army had withdrawn from the war and it was only German soldiers holding the peninsula.
Still, the Fuhrer's troops made the Allies fight for every mile with well-established defensive lines that the 38th Irish and the other Allied forces had to break through. The Irish didn't make it out of Italy and into Austria until May 8, 1945, the same day that Nazi Germany surrendered to the Allies.
Since the men of the 38th (Irish) Infantry Brigade were mostly deserters from the Irish Army, they were officially blacklisted in Ireland from any jobs that received any money from the state and were branded as traitors by both the government and the population.
This punishment lasted for nearly 70 years until a 2013 pardon cleared all men of the Irish Brigade of wrongdoing.
For a more detailed account of the Irish Brigade's exploits in Tunisia and Italy, check out the Irish Brigade's campaign narratives and suggested reading.