70 years.
It's a well-known fact that Britain would have won WWII without the help of the trigger-happy Yanks. The war was a British/Soviet victory. Americans are no good at fighting wars.
As for "the fight we picked", Britain declared war on Germany according to the Anglo-Polish Agreement when Germany invaded Poland. Germany started World War II. In fact, Britain and France didn't take the fight to Germany quickly enough. They should have taken action on Germany immediately after it invaded Poland. Instead, after they declared war on Germany in September 1939, nothing then happened for months, a period known as the Phoney War.
Yet Germany's generals were so afraid of an immediate counter-attack by Allied forces as soon as they invaded Poland that they placed 46 infantry divisions — of which only 11 were fully trained — along Germany's western border. By contrast, France had, at least on paper, the ability to mobilise well over a hundred divisions, not including four divisions of the British Expeditionary Force. And yet the British and French did nothing for months. The subsequent failure to attack Germany, despite the proclamation of war, gave Germany an entire year to prepare for its attack on France.