Seventy years after World War II ended, Japan and Russia are still trying to sign a peace treaty. The persistent bone of contention? The Kuril Islands, seized by Soviet troops in a bloody amphibious landing after Japan announced it was ready to surrender.

But how and why did the Soviets seize the Kurils in the first place?

The Kuril Islands—also known as Chishima or the Northern Territories in Japan—are a chain of fifty-six volcanic islands stretching 810 miles from the northeastern Japanese island of Hokkaido to Russia’s Kamchatka Peninsula. Originally populated by the indigenous Ainu people, the archipelago began receiving Japanese administration during the seventeenth century under the Tokugawa Shogunate.

The Japanese began encountering Russian explorers traveling southward after the settlement of the Kamchatka Peninsula in the eighteenth century. In 1855, Edo Japan and Imperial Russia signed a treaty in which the former claimed the southernmost islands—Kunashir, Iturup, Shikotan and the Habomai Islands—while Urup Island and everything north of it went to Russia. Then an 1875 treaty gave Japan all the Kurils, in exchange for Russia gaining all of Sakhalin, a large island to the west. You can see a map of the island treaties here.

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However, after Japan dealt a shocking defeat to the czar’s forces in 1905, Tokyo got full control of the Kurils as well as the southern half of Sakhalin. In subsequent decades, the Japanese government built up towns, administrative services and infrastructure across the remote islands. Thousands of ethnic Japanese began settling there to fish and mine valuable minerals.

The Japanese carrier task force that bombed Pearl Harbor actually assembled off Iturup Island, profiting from the persistent fogs for concealment. The islands would soon become a target themselves, causing Japan to deploy fighters and two infantry divisions to protect its northern flank. After U.S. forces repelled the Japanese invasion of Alaska, B-25 and B-24 bombers began striking the distant islands in 1943 and 1944, with limited success.

Fuel-starved bomber crews sometimes landed in Soviet territory seeking assistance—but were always interned, as Moscow had signed a neutrality pact with Tokyo in 1938.

That was something Washington was keen to change, as it contemplated the possibility of a bloody invasion of the Japanese home islands. At the Yalta Conference in February 1945, an ailing Roosevelt got Stalin to promise that once Nazi Germany was defeated, the Soviet Union would break the neutrality pact. Stalin stipulated that he would require U.S. military aid, and three months to transfer the necessary forces to the east.

The Yalta agreement also bluntly stated, “The Kuril Islands shall be handed over to the Soviet Union.” After all, the archipelago offered convenient stepping stones for a Soviets invasion of Hokkaido.

Soviet D-Day

Germany surrendered on May 8, 1945. Exactly three months later as promised, the Red Army unleashing a massive ground offensive in Manchuria that swiftly demolished the Japanese Kwantung Army—and also secured the southern half of Sakhalin Island.

Stunned by the loss of China and the U.S. atomic bombings, Tokyo announced on August 15 that it was ready to surrender, and instructed Japanese troops to cease offensive military operations, and to only fire in self-defense. But the same day, the Soviet Second Far East Front received orders to invade the two northernmost Kuril Islands, Shumshu and Paramushiro. Stalin wanted to snatch them before American occupiers arrived.

Unlike their Western allies, the Soviets lacked specialized boats for amphibious landings on defended beaches. But under Project Hula, the U.S. secretly transferred 149 ships to the Soviet Navy through Cold Bay, Alaska—and trained twelve thousand Soviet personnel how to operate them. This included thirty Landing Craft Infantry: forty-eight-meter-long shallow-draft vessels capable of depositing two hundred troops directly onto an unprepared beach.

The Soviet amphibious fleet eventually mustered sixty-two ships, including sixteen LCIs, to transport 8,821 troops of the 101st Rifle Division and a naval infantry battalion. The landing force lacked tanks, and had only the minesweeper Okhotsk to provide heavy fire support with its 130-millimeter gun. However, there were four 130-millimeter shore batteries within range of Shumshu Island on the Kamchatka Peninsula to provide artillery support. In addition, the 128th Composite Aviation Division would assist with seventy-eight warplanes, including two regiments of American P-63 Kingcobra fighters, as well as a mixed regiment of SB-2, Il-4 and A-20 Havoc bombers.

The Kurils were notoriously foggy, and the Soviets had limited opportunity to conduct reconnaissance. The amphibious force set sail early on August 17, and at 2:30 the following morning, the first wave of naval infantry hit the Takeda Beach on the flat, windswept island of Shumshu. The Japanese were taken completely by surprise due to the fog, and initially could not determine which country was attacking them!

However, the defenses on Shumshu and nearby Paramushiro were considerable, including 149- and 105-millimeter shore batteries in concrete emplacements, sixty-four tanks of the Eleventh Tank Regiment and 8,500 troops from the Japanese Ninety-First Infantry Division. The inexperienced Soviet marines failed to capture key Japanese emplacements quickly enough, and the formidable fortifications were swiftly manned by troops of the Ninety-First Division.

Blistering artillery and machine gun fire pinned the follow-up wave on the beach, while heavy batteries began blasting the assembled fleet. Japanese Ki-43 Hayabusa fighters and B5N Tenzan torpedo bombers began swooping down to attack, though several were destroyed by naval flak.

By 9 a.m., five of the crucial LCIs had been sunk, including one carrying a regimental headquarters. The second wave was unable to land badly needed heavy weapons. Troops on the shore could not call for air or artillery support, having lost all their radios.

Takeda’s Tanks in the Breech

Meanwhile, Col. Takeda Sueo’s elite Eleventh Tank Regiment rolled in to counterattack the Soviet beachhead. At first, a company of eleven Type 95 Ha-Go light tanks armed with small thirty-seven-millimeter guns rumbled into battle. The Soviets only had four forty-five-millimeter cannons to shoot back—but dozens of 14.5-millimeter antitank rifles. Obsolete verses German armor, the rifles proved effective against the thinly armored Japanese vehicles, knocking out seven. Still, the tanks pushed Soviet troops back to Mount Severnaya, where they dug into abandoned Japanese positions.

By then Colonel Takeda had arrived with twenty to thirty beefier Type 97 Chi-Ha medium tanks. Takeda’s tanks charged between the crests of two hills, blasting their forty-seven-millimeter guns as antitank rounds smacked into their armor.

In a 1969 memoir, Soviet Major Shutov recalled Takeda’s last moments:

“The tanks formed up and thundered towards us. On one of them, banner in hand, was a Japanese officer. We prepared to deflect the counterattack. I could see the grimace on the officer’s face. I press on thesubmachinegun’s trigger. The officer falls, the banner falls with him. A moment later, his tank stops.”

Soviet infantry resorted to suicidal assault tactics to disable the armored vehicles with antitank grenades—as attested by several posthumous medal citations. In two hours of furious fighting, twenty-one to twenty-seven tanks were destroyed. The rusting wrecks remain on Shumshu to this day, as you can see here.

By the afternoon, the landing force reestablished radio communications, allowing shore batteries and warplanes to pound Japanese emplacements. Soviet marines constructed a temporary pier allowing heavy artillery to be unloaded and join the fight. In the evening, Red Army infantry took advantage of the darkness to creep close to Japanese pillboxes and assault them, clearing away the defenses overlooking the beachhead.

Surrender, Maybe?

The next day, heavy artillery bombardments paved the way for a renewed Soviet advance. But Japanese resistance continued, and a kamikaze plane sank the minesweeper KT-152. But General Fusaki, mindful of orders from Tokyo, dispatched an aid to announce his desire to surrender. The offer was accepted, bringing fighting to a halt at 6 p.m.

But when Soviet ships approached Kataoka airfield the following morning, Japanese troops opened fire with seventy-five-millimeter howitzers, striking the Okhotsk and the patrol boat Kirov. Soviet forces sporadically resumed air and artillery bombardments until August 23 when the last of the garrison finally capitulated. Then through September 1, Soviet detachments made successive amphibious landings into the southern Kuril Islands—and even attempted an airborne landing using Catalina flying boats. At each island, Japanese forces capitulated peacefully.

The Soviet Army and Navy combined lost more than eight hundred dead and over 1,400 wounded in the Battle of Shumshu, compared to 370 Japanese dead and seven hundred wounded. This made it the only battle in which the Soviets suffered heavier losses than the Japanese. The Kurils’ seventeen thousand Japanese civilian residents were deported, while captured Japanese troops were interned in Siberia and employed in forced labor camps. The last survivors returned in 1950.

Japan insists that the southern Kuril Islands accorded to it by the 1855 treaty remain its sovereign territory, as the 1943 Cairo Declaration stated that Japan would only be “expelled from territories seized by violence or greed,” and Imperial Russia had agreed the islands were Japan’s prior to Tokyo’s expansionist campaigns. Thus, the Kurils should be returned based on a language in the Potsdam agreement allowing Japan to retain “such minor islands as we determine.”