Materially the finnish army in ´39 was very badly equipped (hence the molotov cocktails), but the fighting spirit and winter-war prowess carried the 105 days. However new studies show that had the war continued for just a few weeks more, the army would´ve collapsed in critical SE Finland.
BTW the finnish minister of defence at the time, Juho Niukkanen, is freely translated as "John The Meagre" or "John Very Economical" take that as a punch-line for the troopers in a dark wintery night..
