One has to define the beginning of WW2. Several regional conflicts existed through the 1930s. Italy's campaign in Ethiopia and Japan's undeclared war against China for instance. The usually accepted date that WW2 commenced is 1 September 1939 when Germany attacked Poland. Britain and France declared war on Germany on 3 September and at the same so did the constituent members of the British Commonwealth. Other European counties, later members of the Allies, entered the war only when attacked by the Axis. The US only entered the war after the Pearl Harbour attack at the end of 1941, as did US client states such as Mexico and Cuba. As the war swung to the advantage of the Allies, even fence sitting countries or those friendly to Germany and Japan eventually joined the allied cause--Argentina for example declared war on Germany in March 1945 and Chile in April 1945 three weeks before the war had ended.
As the war progressed some countries changed sides. Finland, Hungary and Bulgaria were initially Axis but switched 1n 1944 when German a defeat was inevitable.
Many people whose countries were nominally neutral joined the forces of various countries. Hundreds of thousands of Irish fought mainly in the British forces. After the fall of France, many Frenchmen joined the Free French forces and some joined the Nazi SS as did citizens of Latvia, Lithuania, Estonia and some Balkan countries. Many Palestinian Jews joined the British forces and others mounted terror campaigns against British troops.
Small numbers of US volunteers fought in Allied units before the US entry into WW2, most notable were the Eagle squadrons of the RAF and the Flying Tigers in China.
The full list of countries is too extensive to list here, but the main countries, their date of entry and which side are here.
1 September 1939
Germany (including Austria) Axis
Slovakia (German puppet regime) Axis
Poland Allied
3 September 1939 All Allied
Imperial possessions (includes India (modern Pakistan and Bangladesh), Ceylon, Burma, Rhodesia, Kenya, Tanganikya, Caribbean possessions, Malaya etc.
Australia
France
During September 1939 All Allied
Canada
Newfoundland
Nepal
Czech Government in exile ( Czechoslovakia had been absorbed by Germany in Jan 1939)
April 1940 (After being invaded by Germany)
Norway
Denmark
May 1940 (After being invaded by Germany)
The Netherlands
Belgium
Luxembourg
June 1940
Italy Axis
Oct 1940 ( After being invaded by Italy)
Greece Allied
April 1941 ( After being invaded by Germany, Bulgaria and Hungary)
Yugoslavia Allied
April 1941 All Axis
Bulgaria
Hungary
Romania
Croatia ( German puppet state)
Iraq ( government overthrown by British forces in 1941, thereafter Allied)
Finland
June 1941 (After being attacked by Germany)
USSR Allied
Mongolia (USSR puppet state)
December 1941
USA ( After being attacked by Japan) Allied
China ( Had already been at war with Japan since 1937) Allied
Japan Axis
Korea (Japanese colony) Axis
1942
Brazil Allied
Thailand Axis
Following the attack on Pearl Harbor on December 7 1941.
3rd of September 1939 Because Adolf Hitler invaded Poland. Britain had previously made a pact to defend Poland and they honored it.
Which war?
usa
which war?
The main countries that were first in ww1 ere France, Germany, Britain, and Russia. Later on other countries, including American, joined the conflict.
The original Allies in World War 2 were Great Britain (and it's commonwealth countries), France and Poland. Russia joined later. The United States joined in even later, after the war had been going on for quite some time.
There were many countries that were controlled by Great Britain at the beginning of World War 1.
Britain and France joined the war, becaus Germany invaded Poland. The reason for this is that Britain and France had a pact with Poland, Denmark and Belgium.
which war?
The alliance was between Britain, France, and Russia. Later joined the United States during World War I.
Nazi Germany and Japan .
Britain
well, they joined when britain was at war
France joined on the Allies side with Britain.
allied countries (great Britain,France,russia and japan joined in weeks later,and Italy joined later)
The main countries that were first in ww1 ere France, Germany, Britain, and Russia. Later on other countries, including American, joined the conflict.
The original Allies in World War 2 were Great Britain (and it's commonwealth countries), France and Poland. Russia joined later. The United States joined in even later, after the war had been going on for quite some time.
Scotland is part of Britain and when Britain declared war (August 1, 1914), Scotland automatically joined the war.
The countries that started World War I were Serbia, Austria-Hungary, Germany, and Russia. Those were the base and then more countries joined.
Britain had a treaty to protect the neutrality of Belgium.