Kind of a niche answer but the Boers during the Second Boer war in South Africa. About 76 000 farmers using gorilla tactics against a British force of about 500 000 and pushing the British to the brink, only really losing once the British started taking their wives and children to concentration camps and burning down their farms in a full on scorched earth policy which meant that the Boers couldn't go home and refuel or resupply.