|The countries that formed the Allied was a group that slowly grew during the years the war went by. It was not a pact that was formed from true Allies but from common enemies. As one country after another was invaded or declared on by one of the Axis the group grew. |
We generally consider that World War 2 started when Germany declared the war on Poland on September 1st,1939 and invaded that country. On September 17th, the Soviet Union joined Germany by invading East Poland, activating their part of the Molotov-Ribbentroppact. However, two years earlier on July 7th, 1937, Japan declared war on China. So, it might be fair to say that at least the prelude to World War 2 started on that date. It didn’t start a domino-effect the invasion of Poland did, but it was the first war started by one of the future Axis.
On September 3rd, 1939, both Great Britain and France declare war on Germany. With this declaration they activate their treaties with Poland that they would help the country when Germany would attack them. Most countries of the commonwealth join Great Britain in the days afterwards. The same can be said from the French Colonies. At that moment, the Allied forces consist of Poland, Great Britain, France, and the countries of the Commonwealth and the French Colonies. The invasion of Poland by the Soviet Union remains unanswered by the Allied.
On November 30th, 1939, the Soviet Union declares war on Finland and invades the country that very same day. For a brief time, Finland joins the Allied forces. Again, there are no declarations of war against the agressor but the British and French send some supplies to Finland and even consider sending a force. This idea is abandoned when Sweden doesn’t give a free passage for these troops.
On April 9th Germany declares war on Denmark and Norway and invades these countries the very same day.
One month later on May 10th, 1940, Germany declares war on The Netherlands, Luxemburg and Belgium. With this declaration they invade the Lower Countries and France. On June 10th, Italy joins Germany and declares war on Great Britain and France. One day later they also declare war on Belgium. After the defeat of the Lower Countries and France, Germany aims its arrows on Great Britain.
While the Battle of Britain is in full swing, Italy declares war on Greece on October 28th, 1940. One year later war is declared on Yugoslavia and Italy invades North Africa.
The game changers year are two events. On June 22nd, 1941, Germany starts the invasion of The Soviet Union and that country has to change sides to the Allied and on December 7th, 1941, Japan attacks the Pacific Fleet in Pearl Harbour, forcing The United States to leave their isolationistic policy. When these two giants join the Allies, the equation starts to shift fast. More and more countries are joining The Allied countries from that day on.
From 1943 on, the pressure on the Axis starts increasing. One country after another is forced to leave the Axis and most join the Allies. By the end of the War Germany and Japan have barely any allies left.
|The Allied, Part by date of Declarations of War|
|July 7th, 1937|
|September 1st, 1939|
|September 3rd, 1939|
|September 4th, 1939|
|September 6th, 1939|
|September 10th, 1939|
|November 9th, 1939|
|November 30th, 1939 – December 1st, 1941 (Switched sides)|
|April 9th, 1940|
|April 12th, 1940|
|June 10th, 1940|
|September 9th, 1940|
|October 28th, 1940|
|April 6th, 1941 (Switched sides)|
|June 22nd, 1941 (Switched sides)|
|The Soviet Union|
|The United States|
|December 8th, 1941|
|December 9th, 1941|
|December 12th, 1941|
|January 1st, 1942|
|The United Nations|
|May 5th, 1942|
|May 22nd, 1940|
|June 13th, 1942|
|August 22nd, 1942|
|December 14th, 1942|
|January 17th, 1943 (Switched sides)|
|January 20th, 1943|
|April 7th, 1943|
|September 8th, 1943 (Switched sides)|
|September 9th, 1943 (Switched sides)|
|November 26th, 1943|
|January 27th, 1944|
|August 25th, 1944 (Switched sides)|
|September 8th, 1944 (Switched sides)|
|September 15th, 1944 (Switched sides again)|
|September 21st, 1944|
|December 28th, 1944 (Switched sides)|
|February 2nd, 1945|
|February 7th, 1945|
|February 12th, 1945|
|February 15th, 1945|
|February 23rd, 1945|
|February 26th, 1945|
|February 28th, 1945|
|March 1st, 1945 (Switched sides)|
|March 27th, 1945|