The Metaxas line in the North East of Greece was only really constructed to hold out the Bulgarians, still considered remnants of the "old enemy" the Ottoman Empire. Thus it was considered impractical to be used as part of the Second World War. Although it is recorded that the Nazis who did attack the line became were so enchanted by the valiant defense put up by the few troops obliged to defend it, that they ofered them astounding terms of surrender that I cannot recall happening anywhere else in Europe during the war. Someone might know if there were similar offers made by the Wehrmacht anywhere outside of Greece.
German General Wilhelm List, who led the attack against the Metaxas Line, admired the bravery and courage of these soldiers. He took no prisoners and declared that the army was free to leave with their war flags, on condition that they surrender their arms and supplies. He also ordered his soldiers and officers to salute the Greek soldiers.
So what was the big deal about? Apparently one story has an undermanned fortress about to be overrun by German infantry calling down artillery fire on their own position. following a ten minute barrage, with bayonetts fixed, they proceeded to drive the remaining enemy off the hilltop and in the process took German prisoners. Not what the Wehrmacht at the time were use to, I imagine. Some fortresses were so successful that they captured hundreds of German prisoners. Many Greeks (including officers) refused orders to surrender and held out long after their positions were overrun and their main army had surrendered.
Many of these free Greek soldiers became partizans later, tying up large numbers of German troops for the remainder of the war.