Finnish ski troops bring in Russian prisoners in December 1939 after the battle of Suomussalmi, where the Finns took prisoners and equipment while destroying many tanks.

It sounds like a Berkshire fantasy: Cross-country skiers successfully defend their land against waves of tanks from the Evil Empire. This winter, as Moscow again revs its tank engines on a western border — this time with Ukraine — it is instructive to look back at Moscow’s 1939-40 Winter War with Finland.

At the time, world public opinion was on the side of the Finns. Two weeks after the massive — and unprovoked — attack on Finland, the Soviet Union was kicked out of the League of Nations. About 12,000 volunteers came to help the Finns, including 350 Finns of American descent. But Britain and France, Finland’s major European allies, failed to deliver military aid.

In the end, Finland faced the Soviet Union alone.

The numbers did not favor Finland. The Soviet Union’s population of 168.5 million was 45 times that of Finland’s 3.7 million. The Soviets had 100 times as many tanks and 30 times as many warplanes as Finland. Using a “false flag” incident created by the Red Army, Stalin launched four armies totaling half a million soldiers against Finland. He instructed them to stop at Finland’s western border with Sweden.

Instead of victory dinners of sauteed reindeer in Helsinki, the Red Army walked into a 105-day nightmare.

How the war was won

Cloaked in white capes, Finnish soldiers strapped on their wooden skis, dug their big basket poles into the snow and glided silently through the forests. Using guerrilla tactics, they isolated Russian units and cut their supply lines, depriving soldiers of food, tanks of fuel and horses of oats. In Lapland, Finnish units operated in the almost total darkness of the Arctic winter. They tied up Soviet units five times their size. Up and down the nearly 1,000-mile-long border, Finnish fighters faced tanks, disabling them with crowbars, logs and Molotov cocktails. Alko, Finland’s national liquor monopoly, mass produced Molotov cocktails, complete with matches for easy lighting.

One photo from January 1940 shows Finnish Army officers smirking as they leaf through Red Army ski manuals. These how-to-ski guides were seized after the battle Suomussalmi, a battle where thousands of Soviet soldiers died of frostbite.

For the first two months of the war, Red Army soldiers wore olive green and khaki drab.

This made them easy pickings for Simo Hayha, a diminutive 34-year-old farmer, hunter and amateur marksman. As an Army sniper, he settled into his snow pits before dawn, tamping down the snow to avoid powder puffs from a shot. He preferred a white painted rifle with an old-fashioned metal site. Sunlight reflects off telescopic sites. To minimize telltale breath clouds, Hayha filled his mouth with snow. Although the southern Finland winter only has seven hours of daylight, he managed to kill 500 Soviet soldiers in less than 100 days. One day, he shot 28. On the Soviet side, this invisible sniper was known as “Belaya Smert” — “White Death.”

‘There would be no Finland’

In December 2001, shortly before his 96th birthday, Hayha was asked by Helsingin Sanomat newspaper why he did it. “I did what I was told to do, as well as I could,” said the sniper, whose face was permanently disfigured by a Soviet rifle shot that blew away his lower jaw. “There would be no Finland unless everyone else had done the same.”

Indeed, “the spirit of the Winter War” compensated for the wildly uneven numbers. Only 20 years after a civil war between Reds and Whites, Stalin sought to divide the nation again by setting up a “Finnish Democratic Republic.” Located in a border village, this puppet government was peopled with exiled Finnish Communists — “ministers” — and supported by Finnish language radio broadcasts from Leningrad. Inside Finland, Finns ignored this “government” and united to defend their nation.

After three months of warfare, Finland was exhausted. But so was the Red Army. Today, historians generally agree on these tallies:

Dead, wounded or missing — Finland: 70,000; Soviet Union 350,000.

Lost airplanes — Finland: 62; Soviet Union 500.

Lost tanks — Finland: 25; Soviet Union: 2,500;

Under the peace treaty signed in March 1940, Finland lost eight percent of its territory and had to relocate 12 percent of its population, almost 500,000 people. But Moscow lost big on two fronts.

Adolf Hitler was exhilarated by the poor performance of the Red Army. Emboldened to launch Operation Barbarossa against the Soviet Union in 1941, he chortled: “We have only to kick in the door, and the whole rotten structure will come crashing down.”

In the court of world public opinion, the Soviet Union lost credibility with the Winter War.

Foreshadowing Moscow’s approach toward Ukraine today, the Soviets warned Finnish negotiators in advance that Moscow was being forced to invade in a “defensive war.” By attacking, the Soviets violated three nonaggression treaties signed with Finland.

Once the war started, only the most naive believed Moscow’s propaganda. When the war went badly, Foreign Minister Vyacheslav Molotov blamed 1,000 American pilots. (The Finns had only 114 warplanes.) After the Soviet Air Force fire bombed Helsinki in December 1939, burning 50 buildings and killing 100 people, Molotov told the world press that the Soviet warplanes were dropping humanitarian aid to starving Finns. On the receiving end of 44,000 Soviet air stories, the Finns called the bombs “Molotov bread baskets.”

While the Winter War was featured in Life magazine, it never made it into the pages of Soviet Life. Today, Russian schools largely ignore this debacle.

While Putin may ignore the lessons of the Winter War, Ukrainians would do well to act on the words of Carl Gustaf Emil Mannerheim, Finland’s wartime commander-in-chief: “Forts, cannons and foreign aid will not help unless every man himself knows that he is the guard of his country.”

James Brooke, of Lenox, has traveled to about 100 countries reporting for The New York Times, Bloomberg and Voice of America.