Mannerheim Line

Debate on the strength of the Mannerheim Line[edit]

The first month of the Finnish campaign was humiliating for the Red Army. By the third week of the war, Soviet propaganda was working hard to explain the failure of the Red Army to the populace, and claimed that the Mannerheim Line was stronger than the Maginot Line.^[16] The Finns originally aimed to make its defence line impregnable, however actual construction progress came nowhere close to this goal by the time the Winter War broke out, in contrast to the Maginot Line which effectively deterred a cross-border assault. The Finns had funds and resources for only 101 concrete bunkers; the equivalent length of the Maginot Line had 5,800 of these structures which were also linked by underground railway connections.^[17] The weakness of the line is illustrated by the fact that the amount of concrete used in the whole Mannerheim Line—14,520 cubic metres or 513,000 cubic feet—is slightly less than the amount used in the Helsinki Opera House (15,500 cubic metres or 550,000 cubic feet). The much shorter VT-line used almost 400,000 cubic meters (14,000,000 cu ft) of concrete.


However, "flexible" defense lines (Mannerheim Line, Árpád Line, Bar Lev Line) were not based on dense lines of concrete bunkers and pillboxes (as the Maginot system was). The main intention of flexible type field fortification was to close potential traffic and attack barriers with multiplied anti-tank ditches, hedgehogs, and dragon's teeth. These were followed by a complex system of ditches and barbed wire obstacles, which protected the anti-tank barrier against sappers, bridge-layer tanks, and engineer teams. Therefore, the enemy was forced to attack trenches as in World War I, at the cost of numerous losses, without armor and direct fire support. It was termed "flexible defense" because defending soldiers were not 'locked' into bunkers, but the defensive platoons could be regrouped between field fortifications (wood-earth firing posts, dugouts and pillboxes). They would also have the option of carrying out a counterattack. All soldiers and weapons had multiple firing positions in order to make it difficult to keep them under fire. Concrete bunkers were usually only shelters; just a few had crenels. Concrete pillboxes were side-firing in order to defend anti-tank obstacles.^[14]


Maginot and Siegfried-like bunkers had numerous weaknesses, such as having destructible air inlets and firing holes, being too large (camouflage and costs), and yet being vulnerable to small sapper teams (at Sedan a few German soldiers destroyed several MG bunkers with pre-fabricated bombs and smoke grenades), and being blinded by small concentrated smoke screens. The flexible defense lines were almost immune to small sapper teams or small smoke screens, and had no easily targetable objects.^[14]