1940s
| Year | Date | Event |
| 1942 | 9 October | Australia passes the Statute of Westminster Adoption Act 1942, adopting the Statute of Westminster 1931, but back-dating it to 3 September 1939, when the United Kingdom (and therefore Australia) declared war upon Nazi Germany. Australia becomes a member of the Commonwealth. |
| 1944 | 1 May | The first Commonwealth Prime Ministers Conference convenes in London. |
| 1945 | 4 April | A Commonwealth Statesmen's Meeting convenes in London to coordinate members' demands and expectations of the impending end of the war. |
| 8 May | Nazi Germany surrenders to the Allied Powers, ending the Second World War in Europe. | |
| 15 August | The Empire of Japan surrenders to the Allied Powers, ending the Second World War. | |
| 1946 | 21 February | The British Commonwealth Occupation Force is formed from Australian, British, Indian, and New Zealand occupation forces in Japan. |
| 23 April | The second Commonwealth Prime Ministers Conference convenes in London. | |
| 1947 | 14 August | Pakistan (including modern Bangladesh) joins the Commonwealth upon being granted independence by the United Kingdom. |
| 15 August | India joins the Commonwealth upon being granted independence by the United Kingdom. | |
| 21 October | India and Pakistan begin the first Indo-Pakistani War, over the princely state of Kashmir and Jammu. It is the first armed conflict between two members of the Commonwealth. | |
| 25 November | New Zealand passes the Statute of Westminster Adoption Act 1947 and becomes a member of the Commonwealth. | |
| 1948 | 4 February | Ceylon (modern-day Sri Lanka) joins the Commonwealth upon being granted independence by the United Kingdom. |
| 16 June | Three European plantation managers are killed in Perak, sparking the Malayan Emergency, leading to deployment of Commonwealth soldiers to Malaya. | |
| 11 October | The third Commonwealth Prime Ministers Conference convenes in London. | |
| 31 December | India and Pakistan sign a cease-fire, ending the first Indo-Pakistani War. | |
| 1949 | 31 March | Newfoundland, a dominion until 1934, joins Canada as a province. |
| 18 April | Éire leaves the Commonwealth upon becoming a republic, after the Republic of Ireland Act 1948 comes into effect. | |
| 22 April | The fourth Commonwealth Prime Ministers Conference convenes in London. The agenda is dominated by the impending independence of India and its future within the Commonwealth. | |
| 28 April | The Commonwealth Heads of Government issue the London Declaration. It allows India (and, thenceafter, all other members) to remain in the Commonwealth without having the British monarch as Head of State, creates the position of Head of the Commonwealth, and changes the name of the organisation to the 'Commonwealth of Nations'. |
Read more about this topic: History Of The Commonwealth Of Nations