Most readers would probably assume that with Japan’s World War ll surrender at noon on Aug. 15, 1945, the fighting stopped.

That would be a correct assumption were not the former Soviet Union, which had its eyes on occupying Hokkaido and severing it from Japan, involved.

At 11 p.m. Moscow time on Aug. 8, the Soviet Union informed Japanese Ambassador Naotake Sato that it was declaring war against Japan. In doing so, the Soviet Union was honoring its pledge to the Allies to enter the war against Japan by unilaterally breaking the Soviet-Japanese Neutrality Pact, which was supposed to be effective until April 1946.

An hour later, the Soviet Union initiated hostilities against Japan, entering Manchuria, which had been under Japanese control for the previous decade and a half; Korea, made a part of the Japanese Empire in 1910; and the southern half of Sakhalin (or Karafuto) Island, previously lost to Japan as a result of the Russo-Japanese War of 1904-1905. Tens of thousands died and hundreds of thousands were made prisoners.

The Soviet Union’s maltreatment of Japanese prisoners of war as forced labor — and especially of civilians — much like Soviet forces did to the peoples of Eastern Europe and Germany, is one of the great man-made tragedies of the 20th century, acts for which the former Soviet Union has yet to atone.

On Sakhalin, the Soviet 56th Rifle Corps of the 16th Army attacked the Imperial Japanese Army’s 88th Infantry Division on Aug. 16. While greatly outnumbered, the Japanese defenders — primarily made up of reservists, conscripted students and home guard militias — were able to initially slow the advance of the Red Army. It was not until Aug. 16, the day after Japan officially surrendered, that the Japanese defensive line was broken when the Soviets landed the 113th Rifle Brigade and the 365th Independent Naval Infantry Rifle Battalion in the seashore village of Toro, on the western coast of Sakhalin.

The efforts were aimed at slowing the advance, in part, to buy time to allow for civilians to escape by ship to Hokkaido hours away in dangerous waters. Eventually, Soviet warships (which had been loaned, for better or worse, to the Soviet Union by the United States that spring as part of “Project Hula”) entered the harbor at Maoka (now Kholmsk) on the western coast before dawn on Aug. 20, firing on the town and the 18,000 residents still there (6,000 had barely escaped previously). According to one account, civilians were machine-gunned by Soviet troops who had landed, and approximately 1,000 people were killed.

It was here that the famous Maoka Post Office Incident took place, in which nine female phone operators, who had pledged to stay on during the fighting to relay messages to and from Wakkanai, Hokkaido, eventually committed suicide rather than be possibly raped by invading Soviet forces.

Fighting continued in some areas until Aug. 21, and remaining Japanese units gradually agreed to cease-fires over the coming days. Unfortunately, those seeking to arrange an end to the hostilities were sometimes shot.

In the meantime, on Aug. 22, Soviet aircraft attacked refugees in front of the Toyohara Railway Station, killing hundreds. The same day, Soviet submarines attacked three Japanese refugee transport ships. Survivors in the water were machine-gunned by aircraft. More than 1700 lost their lives.

Another reason for the stiff resistance by Japanese defenders was to prevent the Soviets from occupying Hokkaido, one of Japan’s main four islands. It was Lt. Gen. Kiichiro Higuchi, an intelligence officer specializing in Russian affairs who was then the commanding general of the Sapporo-based 5th Area Army, who was aware of Soviet leader Joseph Stalin’s designs.

In an Aug. 12 order to his troops, he described the Soviet Union as “Japan’s arch enemy (shukuteki)” and committed all his forces to the fight against their attacks on Sakhalin and the Kuril (Chishima) Islands. Despite Japan’s surrender on the 15th, Higuchi was prepared to fight to prevent Soviet landings. He was backed up by the Imperial General Headquarters, which had ordered the end of combat except in self-defense.

On Aug. 16, Stalin wrote to Harry Truman, still just four months into his new role as U.S. president, to request a revision to the draft of General Order No. 1, regarding the handling of Japan. He asked that the “northern half of the island of Hokkaido ... (be included) into the region of surrender by Japanese armed forces to Soviet forces.”

Already correctly distrustful of Soviet intentions, based on Soviet actions in Eastern and Central Europe, Truman would deny Stalin’s request on Aug. 19, but unfortunately allow them to occupy the Kuril Islands (with a request to be allowed use of air bases there).

Two days before, the U.S. also flew a B29 into Chitose Airfield, both to feed and check on Allied prisoners of war but also to send a warning signal to the Soviets. A week later, U.S. reconnaissance aircraft sought to overfly the Northern Kurils to photograph the status of the Soviet occupation, but they were reportedly chased off by Soviet fighters.

In the meantime, Soviet forces attacked the well-fortified islands of Shumshu and Paramushiro in the northernmost part of the Kurils on Aug. 18. Most of the Japanese defenses were eventually destroyed, but at great cost to the invaders. More Soviet personnel died than Japanese. The surviving defenders were sent to Siberia. With this, the Soviets began their conquest of the more lightly defended Kurils, completing those operations on Sept. 5.

Closer to Japan proper, Soviet troops landed on Etorofu, the largest and northernmost of the Southern Kuril islands, on Aug. 28, and on Sept. 1, the day before the planned signing of the surrender documents aboard the USS Missouri in Tokyo Bay, the Soviets seized Kunashiri and Shikotan islands. And on Sept. 4 — two days after the above signing ceremony — it occupied the Habomai Islands group. As readers know, while conditional visits are permitted, the islands have yet to be returned to Japan.

The repatriation of surviving Japanese residents of Sakhalin and the Kuril Islands was completed in 1946. As is so often said, it is the civilians who suffer the most in war.

Higuchi retired in March 1946. The Soviet Union sought to identify him as a war criminal, but GHQ protected him in light of the lobbying efforts of Jewish survivors from Nazi persecution. While serving in Manchuria, Higuchi had arranged for the feeding and safe transport of as many as 20,000 Jews to Shanghai from the Soviet border between 1938 and 1940. This became known as the “Higuchi Route,” the result of which, Higuchi’s name was entered into the “Golden Book” in 1941.

Higuchi is most well known for his humanitarian actions on behalf of the Jews, but his other major accomplishment is preventing the Soviets from occupying Hokkaido and thus causing the division of Japan. His foresight and courage are to be commended.

Robert D. Eldridge is a former tenured associate professor of U.S.-Japan relations and the author of numerous works, including "The Origins of the Bilateral Okinawa Problem" (Routledge, 2001).