Poland

One of the first nations to attack Germany during World War 2 was Poland. Nazi troops crossed the border into Poland in 1939 and started a terror campaign against the populace. However, the Germans were vigorously repelled by the Polish resistance, who suffered heavy losses. With over 260,000 members at its peak, the Polish Home Army (AK) was one of the most significant clandestine armies in Europe.

Despite being vastly outnumbered and outgunned, the AK was able to battle the Germans to a standstill while suffering significant losses. Polish cavalry forces were well-known in the early phases of the conflict. The cavalry was shown to be useless against contemporary artillery and tanks. The Allied invasion of Normandy, Operation Overlord, also benefited greatly from the contributions of the Polish resistance.

The AK helped facilitate the successful charge by smuggling supplies and guns onto the beaches and undermining German fortifications. Despite Poland's heroic efforts, the Germans finally won the war and occupied it for its entire duration. The Polish resistance, however, will go down in history as one of the most valiant.