Yes and no.

Historians and contemporaries of the time have identified a "golden age of Canadian diplomacy," where Canada had a role on the world stage that outclassed its small and relatively moderate power in the years after the Second World War. One diplomat, Escott Reid, identifies these years as 1941-1951 and includes the Second World War (1939-45) and specifically after the Fall of France in 1940 after which Canada stood alone as Britain's major ally until the American entry in December 1941. To him, Canada's role as Britain and America's primary ally, its role in the invasion of Europe, and its ability to act a middleman between the two major Allied powers, gave its the diplomats to ability to truly impact international affairs in a way never seen before or since. Canada helped to win the Second World War, signed major international agreements with its allies, helped shaped the United Nations in 1945 and to create NATO in 1949, and ultimately was playing with the "big powers" even it wasn't one.

Reid's assessment has been challenged during his time in External Affairs and since. Some historians argue that Canada's golden age begun in 1946, after the Second World War, and lasted until 1957 when John Diefenbaker became Prime Minister. They stress the partnership between Prime Minister Louis St Laurent and his Minister of External Affairs (and future Prime Minister in 1963) Lester B Pearson. Together, they forged a path for Canada through the tumultuous beginnings of the Cold War, the Korean War, and the Suez Crisis. Pearson's role in the Suez garnered him a Nobel Peace Prize, as he was one of the primary architects behind the UN intervention between the armies of Egypt, Israel, Britain and France, and perhaps avoided the breakout of a larger conflict in the Middle East. These historians tend to chose a later date because Prime Minister Mackenzie King, who was replaced by St Laurent in 1948, was isolationist before and after the Second World War (and arguably during as well, but had little choice in the matter). His time as Canada's leader diminished its impact on foreign affairs in their eyes, and Canada's international role only reached its peak after his departure.

Pearson and his fellow diplomats tried to create a role for Canada in the Cold War world of superpowers by becoming a "middle power." Canada acknowledged its close ties with the United States (and Britain, but less post-1945), yet also understood that Canadian interests may some times not align exactly with their southern neighbour. When it was necessary and prudent, Canada would use its international influence to affect issues that it considered important. Canada tried to offer mediation and conciliation, given it could not force other nations to agree with them like the US or the USSR. This was probably epitomized in Pearson's role in mediating the Suez Crisis in 1956 and pioneering our role in "peacekeeping" and resolving conflicts with diplomacy rather than ending them through force.

A lot of attention has been given to explaining this golden age and Canada's supposedly innovative approach to international affairs, regardless of what range of years we assign to it, but it's not entirely accurate. The era certainly saw an increased stature for Canada, but some historians have argued that this was a quirk of the time: Europe was in ruins, the communist nations were isolated and hostile, and Canada, having avoided the destruction of the Second World War, was in a unique place to ascend to a "higher rank" in international affairs. Ultimately though, their influence was illusory - as the "decline" after 1957 (or 51 if you accept Reid's assessment) demonstrates. Canada certainly played a larger role on the international stage, but surely it was a much smaller stage. If Canada was so influential and noteworthy, how can we explain how quickly it is lost?