When I was younger and read books about World War II written in the late 1940s and 1950s, I came away with the idealized wartime notion that despite a few cultural differences, the alliance between the United States and Great Britain was a case study on how two nations with shared values and a common enemy could - and should - cooperate to wage and win a global war.

A case in point: If you read Cornelius Ryan's famous 1959 classic about D-Day, The Longest Day, you won't find any references to the sometimes vitriolic disagreements between American and British war planners about where and when the Allies should mount offensives against Adolf Hitler's Third Reich. Instead, you'll read about how well-planned and organized the Overlord operation was and how gutsy all the soldiers seemed to be as they landed on the five invasion beaches in Normandy.

Only in Ryan's later books about the European campaigns - 1966's The Last Battle and 1974's A Bridge Too Far - do readers get a more honest account of the tensions between American and British generals, especially at the higher levels of command.

Indeed, as the years march by and more historians gain access to more records and private communications (letters, journals and unpublished memoirs), World War II buffs and other readers get a fuller and more nuanced look at the war, its big (and small) battles and the people who lived through it.

Lynne Olson's Citizens of London: The Americans Who Stood With Britain in Its Darkest, Finest Hour focuses primarily on three prominent Americans - Ambassador John Gilbert Winant, Lend-Lease coordinator Averell Harriman and CBS correspondent Edward R. Murrow - who played a vital role in aiding Great Britain when she virtually stood alone against Hitler, then transformed the island nation into the springboard for the Allied invasion of France and the liberation of Europe.

The book starts - after an introduction set in 1947 that serves sort of like a movie's "flashback setup" - in March of 1941 as King George VI, in an unprecedented break from protocol, greets the incoming Ambassador of the United States to the Court of St. James at a railway station in Windsor with an extended hand and says, "I am glad to welcome you here."

Winant, who was replacing the pessimistic and controversial Joseph P. Kennedy, had been a prominent professor, World War I veteran and a three-time Republican governor of New Hampshire before Roosevelt asked him to be the first director of the Social Security Board then later served on the International Labor Organization in Geneva, Switzerland.

Where Kennedy had been an irritant to Prime Minister Churchill and President Roosevelt (he had ordered the evacuation of most Americans from London during the Battle of Britain and resigned after a controversy stirred up by some ill-timed public remarks which seemed to predict a Nazi victory in the war), Winant was determined to show the war-battered British that the U.S. supported their fight against Nazi tyranny even at a time when most Americans were isolationists and wanted to keep the country out of "European wars."

One of Winant's chief allies in making sure American public opinion shifted in Britain's favor was the famous CBS correspondent Edward R. Murrow, who had been assigned to the radio network's London bureau since 1938 and distinguished himself in a series of broadcasts during the Battle of Britain and the "blitz" on London which followed.

Living in the British capital with his wife Janet, Murrow - whose "This...is London" tagline became famous to radio listeners of the time - was convinced that fighting Hitler was necessary and vital for the survival of the United States, and he endeavored to turn public opinion in this direction. But isolationism and Republican opposition to any American involvement in the war was so entrenched that not even the sinking of a U.S. destroyer and damage to several others caused a big enough stir. Only the Japanese attack on Pearl Harbor - and Hitler's suicidal declaration of war against the U.S. on December 10, 1941 - aroused the American people out of its insular and naïve attitude that it could remain forever neutral.

The third key player of Citizens of London is Averell Harriman, Roosevelt's Lend-Lease coordinator for Britain and - later - Ambassador to the Soviet Union. Young, ambitious and quite the ladies' man, he was responsible for the program which provided arms, food and munitions to Britain under the terms of the 1941 Lend-Lease Act.

He also, much to Ambassador Winant's chagrin, tended to act as Roosevelt's personal representative in London, often bypassing the appointed head of the U.S. Embassy and keeping Winant "out of the loop." (Ironically, Harriman would often be in a similar situation when he was the American ambassador to the Soviet Union, as Olson points out in later chapters.)

Though Citizens of London focuses on the diplomatic and military aspects of the alliance between the U.S. and its "mother country," it also delves into the private lives of Winant, Murrow and Harriman, all of whom were married men yet, succumbing to the stresses and temptations of living in a city literally under the bombs, had affairs with prominent British women - Winant with Churchill's actress daughter Sarah, Murrow and Harriman with the Prime Minister's daughter-in-law Pamela.

Olson also takes a wider view of the Anglo-American alliance and writes a great deal about the efforts of Gen. Dwight D. Eisenhower to foster a real "inter-Allied sense of teamwork" even though many American generals (George S. Patton, Mark Clark, Omar Bradley and even Ike's boss George C. Marshall) were Anglophobic to some extent.

Conversely, many British generals, including Chief of the Imperial General Staff Alan Brooke and Field Marshal Bernard Montgomery, thought Ike and the American military as a whole were callow, naïve and not "real soldiers." They resented America's non-involvement in the war for the first two years, and even when it was obvious that U.S. military power in Europe was preponderant while Britain's was declining, they tended to believe that American strategy and tactics were inferior to their own.

Another side story Olson writes about is the role played by former World War I pilot and champion polo player Thomas Hitchcock in one of the key decisions of World War II: the development of the P-51 Mustang, a warplane originally intended for the use of the Royal Air Force. In her chapter about this topic, Olson showcases the grit Hitchcock displayed to convince a narrow-minded Army Air Corps brass to adopt and refine the fighter plane which would most contribute to the Allied victory in Europe.

The most eye-opening chapters, though, are the ones which reveal the deterioration of the relationship between FDR and Churchill, especially after 1943 when the President wanted to establish a post-war partnership with Josef Stalin and the Soviet Union.

In Citizens of London, Olson shows how a clearly shallow and anti-colonialist Roosevelt not only hurt Churchill's feelings about the British Empire, but clearly had no notion of how to deal with the serious problems Europe would face after the defeat of Hitler's Germany.

Though some readers may not relish Olson's sometimes dishy looks at the private lives of the three key Citizens of London, I think that by delving tastefully into the often bittersweet romances Winant, Murrow and Harriman had during their stay in Britain the author humanizes them. It might have been morally wrong for them to have wartime romances with married women while they themselves had wives, but stress, the sense of "live for today for tomorrow you may die" and even the adrenaline rush of war itself often drives people into situations which in normal times they'd avoid.

Olson, who co-wrote The Murrow Boys with her husband Stanley Cloud, manages to blend a big-picture look at her subjects' public lives with tastefully-written intimate glimpses at their private ones. Her prose is lively and her tone is factual without veering off into either overwhelming didacticism or sensationalistic voyeurism.