Modern parallels to the 300 at Thermopylae?

Leo Major and twenty French Canadians held off two entire Chinese divisions during the Korean War long enough for reinforcements to arrive and relieve them.

The defenders of Wake Island and Bataan deserve a mention, as well.

Every battle Armenia ever fought. If you want a more Western example you could look at the lost battalion, where 500 Americans in World War 1 got stuck behind enemy lines and refused to surrender to the 10,000 or so Germans who surrounded them and hit them with everything from artillery to flamethrowers.

This happened continually in WW 2 as the Germans were escaping from Russia. The rear guards would hold off the advancing Russians innumerable times costing all the German lives. All that sacrifice - perhaps of 1/2 million guys - as gone unrecorded and unremembered.

Wake Island, "The Alamo of the Pacific."

depends on scale

in afghanistan at a small brit out post

it was attacked by like 40 taliban

and ion the initial attack, every brit there was killed or wounded bad enough they could not fight

except for on Gurka -- who for a couple of hours, fought off all 40 taliban by himself, until help arrived

he was awaded britians 2nd highest medal for valor ( gurkas cannot earn the victoria cross ) so he got the highest medal they could give him