Two days after Germany invaded Poland in September 1939, Britain and France declared war on Germany, and World War II erupted. Dozens of countries, still recovering from the horrors of World War I, tried to remain neutral to avoid invasion and more bloodshed.

But a declaration of neutrality did little to insulate countries from the conflict if they were geographically desirable. “The fact that the coast of Norway straddled the North Sea made it an area of critical importance to both Great Britain and Germany,” says Dr. David Woolner, Marist college professor and author of The Last 100 Days: FDR at War and Peace. “It was this fact that led to the German invasion of Denmark and Norway in April 1940, and to the British decision to intervene in the neutral Danish territory of Iceland shortly thereafter.”

It was true for other countries as well—including Belgium and the Netherlands, both of which had declared their neutrality prior to the war. Their neutral status made little impression on Adolf Hitler, who ordered his forces to invade both states as part of his attack on France in May 1940. Meanwhile, the Soviet Union invaded Lithuania, Estonia and Latvia in June. This enabled Soviet leader Joseph Stalin to expand power, Woolner explains, and create a buffer between the USSR and Germany.

“In short, staying neutral in an ever-expanding war proved virtually impossible for these nations,” he says.

The United States, protected by two vast oceans, however, stayed neutral for more than two years despite finding ways to help the Allies. It officially entered the war after the Japanese attacked Pearl Harbor on December 7, 1941.

Only 14 countries remained officially neutral throughout the entire war. They included Sweden, Switzerland, Spain, Portugal, Ireland, Turkey, Yemen, Saudi Arabia and Afghanistan as well as the microstates of Andorra, Monaco, Liechtenstein, San Marino and Vatican City.

But even those states that managed to stay out of the war, such as Sweden and Switzerland, found their ability to maintain strict neutrality hampered by the intensity of the conflict, Woolner says. The result, he adds, is “they played a somewhat ambiguous—and still controversial—role in the war.”

A seminal 1998 U.S. State Department report helped dispel the myth that there was any standard form of neutrality, citing that the neutral countries continued trading with the Allied and Axis forces, sent troops to offer military assistance, and allowed one side or the other access to its territory.

Perhaps the largest finding from the report was that the Nazis purchased critical war material from neutral countries using Swiss francs gained in exchange for gold looted by the Nazis from occupied countries and from individual victims of concentration camps. These materials included tungsten from Portugal and Spain; ball-bearings and iron ore from Sweden; and chromite ore from Turkey— all critical to the German war effort.

Although the neutral countries often cited fear of German reprisals as their motivation for maintaining trade with Germany, the report found that many continued well into 1944, while Switzerland continued to trade until the end of the war in 1945.

The report also noted the military assistance offered by neutral countries. Spain, whose civil war had just ended at the beginning of World War II, sent troops to the Russian front to help German armed forces. Portugal granted access to the British to its bases in the Azores. Sweden allowed German troops across its territory to reach Finland in order to fight against Soviet occupation forces, as well as to facilitate the occupation of Norway. It also protected German shipping in the Baltic.

Decisions and actions even of a single country were often inconsistent. Argentina traded more with the Allies than the Axis powers, yet its wartime leaders leaned toward fascism; it was a center for Axis espionage, smuggling and propaganda; and it was long suspected for being the destination for Nazi looted assets.

Despite these conflicting actions, the neutral countries offered refuge to 250,000 Jews fleeing the Holocaust, though each country’s response was unique. The authors wrote, “Acts of humanity and even heroism rose above the harshness or insensitivity of wartime refugee policies and reflected well on their governments and peoples.”

The report concluded that the neutral countries were able to maintain their status because of their distinctive history, geography, previous relationships with wartime belligerents and, with Sweden and Switzerland, historical traditions of neutrality. They all faced similar pressures from both the Allied and Axis power, but their responses varied considerably. As the report concludes, “There was, in short, no such thing as uniform or absolute neutrality during World War II.”