This timeline is virtually the same as the actual WW2 timeline for the first few months, and therefore only major changes or events will be noted.
- June 24 - De Valera gives in to Churchill's request to join the war against Nazi Germany, realizing that it would be in his country's best interests to aid the British. He tells Churchill he will have the Dáil vote on it.
- June 25 - A vote is held in the Dáil to decide whether or not to join Britain in the war against Nazi Germany; the majority votes "yes".
- June 26 - De Valera makes an announcement to the Irish people officially declaring war on Nazi Germany. De Valera explains his and the Dáil's reasoning in the address, stating that it was in the best interest for Ireland. He began ordering his generals to prepare their troops for transport and combat.
- Luftwaffe begin bombing British and Irish cities; Battle of Britain begins.
- Irish ships are dispatched to send aid to the British in Malta.
- Anti-war protesters being protesting in Dublin; de Valera assures them the decision to enter the war is "in Ireland's best interests".
- De Valera and other politicians manage to settle the disgruntled people down during this month, and most protests end.
- Irish troops from the First Division meant to be sent to British Somaliland are instead stationed in Egypt after the Italian Army takes the capital of Berbera.
- September 9-13 - Italian Army launches an invasion of Egypt and take the small port of Sollum.
- September 16 - Italian advance comes to a stop after troops dig in near Sidi Barrani.
- September 17 - An Anglo-Irish force consisting of two Irish infantry brigades, two British infantry divisions, and a British armored division, clash with the Italian forces near Sidi Barrani, resulting in a the Italians being forced back towards Sollum.
- September 19 - Anglo-Irish force launch an assault on Sollum, spearheaded by two Irish battalions, taking the port and effectively forcing the Italians out of Egypt.
- September 23-25 - A couple hundred Irish soldiers accompany the failed invasion of Dakar.
- October 2-30 - Along with London, Dublin continues to be bombed.