Today, September 1, 2026, marks exactly 87 years since the outbreak of World War II. For Poland, this date carries a particularly painful significance. On September 1, 1939, Nazi Germany invaded Poland, beginning a war that would devastate Europe and claim millions of lives.
The attack began in the early hours of the morning. German aircraft bombed Polish towns and cities while German troops crossed the border. One of the most famous symbols of the first days of the war was Westerplatte, a small Polish military outpost whose defenders held out for seven days against a vastly stronger German force. The town of Wieluń was also bombed, with civilians among the first victims of the German attack.
The situation became even more desperate on September 17, 1939, when the Soviet Union invaded Poland from the east. The two totalitarian powers had secretly agreed to divide parts of Eastern Europe between themselves in the Molotov-Ribbentrop Pact, signed shortly before the war.
Poland was now fighting on two fronts.
By the end of September 1939, Poland's regular military resistance had been defeated. But the Polish state did not simply disappear.
The government escaped abroad and continued to operate from exile. Inside occupied Poland, an extraordinary underground system began to emerge: the Polish Underground State.
It was far more than a resistance movement. It had underground administration, courts, a press and even a secret education system. Teachers organized underground classes, where Polish children secretly studied history, literature, mathematics and other subjects despite German restrictions.
At the same time, a military resistance movement was being organized. After several transformations, it became the Home Army (Armia Krajowa, or AK) in 1942.
The Home Army became the main armed force of the Polish Underground State and one of the largest resistance organizations in occupied Europe.
Its members gathered intelligence, carried out sabotage, attacked German infrastructure and transported weapons and information. Resistance fighters often lived double lives: during the day they could be ordinary students, workers or clerks, while at night they secretly carried out missions.
One of the most famous groups within the resistance was the Grey Ranks (Szare Szeregi), the underground branch of the Polish Scouts. Many of its members were teenagers. They initially carried out acts of “small sabotage,” such as painting resistance symbols on walls and removing German propaganda, but some eventually took part in armed operations.
In March 1943, the Grey Ranks carried out the famous Arsenal Action, rescuing Jan Bytnar, code-named “Rudy,” from German custody. He had been brutally tortured by the Gestapo and died several days after his rescue. His story became a symbol of the young generation that grew up under Nazi occupation.
By 1944, the Soviet Red Army was advancing toward Polish territory. The Home Army launched Operation Tempest, attempting to fight the Germans and demonstrate that Poland had its own legitimate government and armed forces.
The greatest and most tragic example was the Warsaw Uprising, which began on August 1, 1944, at 5:00 p.m.
Thousands of Home Army fighters attempted to liberate Warsaw from German occupation. The fighting lasted 63 days. Resistance fighters battled through streets, ruined buildings and underground sewers, while German forces responded with overwhelming force and mass executions.
Tens of thousands of civilians were killed, along with thousands of resistance fighters. On October 2, 1944, the remaining Polish forces surrendered, and Warsaw was subsequently devastated by the Germans.
The uprising remains one of the most powerful symbols of Polish resistance, although historians continue to debate whether it had a realistic chance of success.
Germany was defeated in 1945, but for Poland the end of the war did not mean the return of full independence.
Poland fell under Soviet domination and a communist government was established. Many former resistance fighters refused to accept the new political order and continued underground resistance. They later became known as the “Cursed Soldiers” (Żołnierze Wyklęci).
Their history is complex, and different groups had different goals and methods. For many Poles, however, they represented a continuation of the struggle for independence.
One of the most recognizable symbols of the Polish resistance was the “Kotwica,” - Anchor, representing Polska Walcząca - “Fighting Poland.”
Painted secretly on walls across occupied cities, it carried a simple message:
Poland is still here.
The Polish state had been invaded and occupied. Its cities were destroyed and millions of its citizens were killed. Yet underground officials continued their work, teachers continued to teach, newspapers continued to be printed, and resistance fighters continued to fight.
That is why the Polish experience of World War II is not only a story of defeat in September 1939.
It is also a story of resistance, survival and the determination to keep Poland alive when its enemies wanted it to disappear.
Eighty-seven years after the invasion began, September 1 remains a day of remembrance in Poland, not only for how the war started, but for the people who refused to accept that Poland had ceased to exist.