Whenever a liberal tells me it is naive to think small arms can defeat heavy weapons (i.e. modern US Army) I remind them about Ethan Allen. In 1775, the siege of Boston by the incredibly powerful British Army was broken, in part, by US artillerymen using heavy weapons (cannons) that Ethan Allen and the Green Mountain Boys, using only muskets, liberated from the English at Fort Ticonderoga.
That will be dismissed as “ancient history”. Cite Vietnam and more recently the Soviet-Afghani war - especially the latter, as the only “heavy weapons” they had were antiaircraft missiles provided by the US and they still managed to run Russia off.