For a month 100 years ago, a quiet New England port held the focus of the world. From Aug. 9 to Sept. 5, diplomats were thrown together with local ladies clubs, and foreign reporters swooped onto picket-fenced streets and called the town a beacon of hope to end the cataclysm between "East" and "West." In fact, the Russo-Japanese War of 1904-05, fought mostly in Manchuria, was so profound in its effect that some historians now call it "World War 0."

Today the 1905 war is often little more than a footnote. It has been marginalized and dwarfed by the horrors of World Wars I and II. Yet a century later historians say the conflict marked a series of crucial global turning points: It opened what historian Herbert Bix calls a "new era of imperial rivalry in Asia and the Pacific." Japan began its rise. The war was unique: Fought between two powers, Russia and Japan, within the boundaries of two neutral countries, China and Korea.

The war showcased modern hardware and tactics. Improbably, the peace was brokered by a third party, the US, in a debut international performance.

The war showcased modern hardware and tactics. Improbably, the peace was brokered by a third party, the US, in a debut international performance.The scale and severity of the clashes, and the possibility that Europe might join in, frightened the entire world. Japan lost 110,000 soldiers in the first year. Russia's great Baltic Navy steamed four months to the Pacific - then lost 16 battleships in 36 hours in the Tsushima Strait. After 18 months Russia didn't win a battle. Its proud image was shattered. Japan destroyed the myth of European invincibility, but was nearly bankrupt. Neither side wanted talks. Neither wanted a mediator.

But President Theodore Roosevelt stepped into the fray, hosting 30 days of negotiations that resulted in a peace pact - and America's first Nobel Peace Prize, awarded partly for a diplomatic approach later called "multtrack."

The Sakhalin and Kurile islands, whose ownership was still under discussion last month in Tokyo at a meeting between Russian and Japanese heads of state, were the central sticking point in the Portsmouth treaty, and nearly scuppered the deal. Chief Russian diplomat Sergius Witte twice pocketed cables from Czar Nicholas asking him to come home.

For Russia, the war was a disaster for the Czar; grumbling in the streets added to unhappiness leading eventually to the rise of the Bolsheviks.

In Japan, the war had an opposite effect: It brought Japan international prominence, and stoked pride. The event closely melded military and emperor - and set the stage for Japan's push through all of Asia. Emperor Hirohito, says Mr. Bix, grew up playing childhood military games from the Russo-Japanese War. Later, on the eve of Pearl Harbor, Japan refused to leave Manchuria, arguing that to do so would "give up the fruits of the ... Russo Japanese War," as Hara Yoshimichi, privy council in Tokyo, put it. Naval tactics, especially Japan's "single blow" approach against the Russian navy, prefigured Pearl Harbor.

It would be hard to overstate how transfixing the war was at the time. "The loss of life was terrible on both sides," says Peter Randall, a Treaty of Portsmouth historian. "In the Port Arthur battle the Japanese kept attacking and attacking, and with modern weapons the severity was frightening. The entire world was watching. "

Concern ran so high that many American churches held services for peace. The founder of this newspaper, Mary Baker Eddy, asked her church members to pray daily for peace from June 17 to July 1 1905.

Today, Japanese and Russian historians tend to downplay it as a "regional conflict." However, a major exhibition of 1905 war artifacts just closed at the Yushukan museum in Tokyo, and presented the war as a glorious moment in Japan's rise.

For the 100th anniversary in Portsmouth earlier this year, local groups put on an exhibit at the John Paul Jones House, hosted two state dinners and historical reenactments, and developed a curriculum, a traveling exhibition, and a website (www.portsmouthpeacetreaty.com).