Although the Russo-Japanese War (1904-1905) was the first major conflict of the 20th century, it has been largely forgotten, having been overshadowed by subsequent clashes including two World Wars.

However, it remains important for two reasons: It was the first war in which an Asian nation defeated a European one; and the first war that employed large, steam-powered naval fleets with modern, long-range artillery, torpedoes and torpedo boats.

Fighting began when the Japanese navy launched a surprise attack on a Russian fleet anchored in Port Arthur, a base in the Yellow Sea that was later captured by the Japanese army.

It ended May 15, 1905, when Adm. Heihachiro Togo destroyed a Russian fleet in the Battle of Tsushima in the Korea Strait, sinking 22 ships and Russia’s chances of becoming a Pacific naval power.

Russia was compelled to sue for peace, which was eventually brokered by President Teddy Roosevelt.

The focus of Constantine Pleshakov’s book, “The Tsar’s Last Armada,” is the extraordinarily long voyage of that ill-fated Russian fleet, which sailed from the Baltic Sea to the Far East. The fleet, sent on orders of Czar Nicholas II and commanded by Adm. Zinovy Rozhestvensky, had two goals: to avenge the losses suffered at Port Arthur and defeat the upstart Japanese navy.

The voyage covered 18,000 miles and took nine months. The Russian armada was assembled painfully slowly. It included a handful of fairly modern battleships but also several obsolete cruisers, rust-bucket transports and unreliable torpedo boats. Most of the officers were inexperienced in fleet maneuvers, crew training was abysmally insufficient and many of the men had been inmates drafted from prisons.

There were other bad omens. Several European nations prohibited the ships from putting into ports en route to take on supplies and coal. And there was the possibility of sabotage and surprise attacks by Japanese spies and agents, since it was hard to hide the movements of such a large fleet whose destination was known.

The armada came across a fleet of British fishing vessels one night in the North Sea. Mistaking them for Japanese torpedo boats, the Russians attacked, sinking one trawler and damaging several others. The episode created a diplomatic uproar and aroused England’s hostility toward Russia.

Near Madagascar, the fleet anchored for more than two months to await the arrival of more ships Nicholas had belatedly decided to send as reinforcements.

The ill-tempered Rozhestvensky, nicknamed “Mad Dog,” was infuriated by the czar’s decision. He considered the additional ships unnecessary and saw the delay as an advantage for Togo, giving him time to overhaul his fleet and retrain his crews.

Rozhestvensky sailed from Madagascar without waiting for the additional ships. As the Russian fleet entered the Sea of Japan, in the narrow Korea Strait, it found Togo’s ships waiting. Within a few hours, all the major Russian battleships had been sunk. The rest surrendered or fled.

Pleshakov’s book provides many details about the long, difficult and disastrous voyage, and familiarizes readers with the personalities of Rozhestvensky and many of his officers. Despite being documented and annotated, the narrative is fluid and very readable.

“The Tsar’s Last Armada” is a welcome reminder of an important and long-forgotten event in naval history.