While Japan allied itself with Germany and Italy during the Second World War, it didn’t support the 1939 invasion of Poland. In fact, the empire actively supported the Polish government-in-exile at the start of the conflict – that is, until the European country sent a declaration of war in 1941. Surprisingly, this little-known war lasted 16 years.
Polish and Japanese cooperation
Cooperation between Japan and Poland dates back to the 1904-05 Russo-Japanese War. During this time, activists vying for Polish independence cooperated with Japanese intelligence, providing them with information about the movement of Russian troops. In fact, despite Poland not yet being recognized as an independent country, it was deemed a “Samurai Nation” by Japanese author Nitobe Inazō in his 1904 book, Bushido: The Soul of Japan.
After the First World War, Japan officially recognized Poland as an independent state. This marked the beginning of international relations between the two countries. After the conflict, Japan supported Poland’s efforts to join the League of Nations as an independent nation.
In 1923, the Polish military taught the Japanese Army cryptography, sending officers to Japan to teach encryption skills. The Japanese had been struggling to break Soviet radio signals for over a year at this point. With the help of the Poles, they were cracked in just a few weeks.
Outbreak of the Second World War
Despite having different allies at the start of the Second World War, Japan and Poland continued their strong relationship. This was heavily influenced by distrust of the Germans upon entering into a secret pact with the Soviet Union, prior to the invasion of Poland in September 1939.
After the outbreak of World War II, a Polish espionage network was created at the Japanese embassy in Berlin. Polish agents and diplomats traveled on passports provided by the Japanese.
Poland declares war on Japan
The relationship between Poland Japan changed following attack on Pearl Harbor on December 7, 1941. Immediately after, the United Kingdom declared war on Japan, along with its dominions and Allied governments-in-exile. This included Belgium, the Netherlands, the French National Liberation Committee and, eventually, Poland.
On December 11, 1941, the Polish government-in-exile reluctantly declared war on Japan. However, the Japanese politely refused, making the declaration legally void. Japanese Prime Minister Hideki Tojo stated, “We do not accept Poland’s challenge. The Poles, fighting for their freedom, only declared war on us under pressure from the United Kingdom.”
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This state of war only existed on paper, and cooperation continued between Poland and Japan throughout the remainder of the Second World War. The Poles kept giving the Japanese intelligence on the USSR and Germany, in exchange for passports. This state of war existed for 16 years, until it was formally dissolved in 1957 with an agreement to restore a normal relationship between the Polish People’s Republic and Japan.