WWII
Guerrilla War in Poland
After the Poland surrender some groups of men from the army continued the fight hiding in the forests. The germans and russians unleashed a terror wave, including mass executions and deportations.
When France was invaded by the germans a new wave of attacks and sabotage acts took place. But the attacks weakened the partisan army strenght to a point where they should be cancelled.
During 1941 the action begun to be coordinated from London by radio, and by british spies dropped over the country who also carried weapons and supplies to the guerrilla warriors.
When the german invaded the Soviet Union the partisans attacked the german supply line. They blew bridges, railroads, trains and weapons factories. They also attacked the ammo and reinforcements convoys.
Finally in 1944 when the Russian offensive approached Warsaw the partisans begun an insurrection that took control of the city. The Russians could have helped them but due to political reasons they ceased their advance until the germans destroyed the rebellious army, so they can conquer the country with no native threats to their power.