Russians abandon Osowiec

On 22 August 1915 the last units of the Russian garrison left the fortress of Osowiec on the Biebrza, in today’s Podlaskie Voivodeship. Only sappers remained, preparing the forts for demolition. The British chronology of the war recorded under this date that the Germans had taken Osowiec by storm. That was not the case. The fortress, which since February had repulsed German attacks, bombardment by the heaviest guns and a gas attack, was abandoned on the orders of the Russian command, because after the collapse of the front in the Kingdom of Poland its further defence had become pointless.

Half a year of siege

Osowiec blocked the only passage through the Biebrza Marshes on the road from East Prussia to Białystok. From mid-February it was besieged by the German 11th Landwehr Division. At the turn of February and March dozens of heavy guns shelled it, including 305 mm and 420 mm mortars, but the forts held and the infantry kept its forward positions. On 6 August, after more than ten days of waiting for a favourable wind, the Germans released onto the Russian positions a cloud of chlorine, mixed with bromine according to Russian sources. Several companies of the 226th Zemlyansk Infantry Regiment were wiped out almost entirely, and the Landwehr broke into the trenches. A counter-attack by the gassed soldiers, which Russian literature later called the “attack of the dead men”, nevertheless threw the Germans back to their starting positions.

The order to retreat

The assault had been repulsed, but the fate of the fortress was being decided elsewhere. On 5 August the Germans entered Warsaw, in mid-month they broke through the Russian positions on the Narew, and on 17 and 18 August they took Kovno. The Russian armies were retreating eastwards, and Osowiec became the westward-projecting right flank of the front. The fortress commandant, General Nikolai Brzhozovsky, received orders to evacuate, which according to Sergei Khmelkov, a participant in the defence and later the fortress’s historian, began on 18 August. Several trains with guns managed to leave for Białystok before rail traffic stopped on 20 August. The soldiers hauled the remaining heavy guns with ropes at night along the highway to Grodno, because by day the road was watched by German aircraft. Stores were taken away by lorries and carts, and where possible the civilian population was evacuated as well. The garrison assembled at Suchowola, where it was formed into a separate corps under Brzhozovsky’s command.

On 22 August units of the German Eighth Army crossed the Biebrza in the area of Strękowa Góra and cut the railway from Osowiec to Białystok south of Knyszyn. The fortress, cut off from its rear, could no longer stop anything.

The explosions

Two companies of sappers, fortress engineers and the crews of four guns remained in the abandoned fortress. The guns fired all day to hide from the Germans the fact that the garrison had left. According to Khmelkov, on the evening of 23 August the sappers set fire to the barracks and buildings, and from 8 p.m. began blowing up the forts, batteries and shelters with charges of a ton or more of pyroxylin each. Finally they blew up the last guns and left for Suchowola. The German war communiqué of 23 August announced that on the Biebrza “the fortress of Osowiec, abandoned by the Russians” had been occupied. According to Khmelkov the Germans entered the ruins only on 25 August. Sources thus differ as to the day, but agree that the fortress was not taken by storm.

In Russia the defence of Osowiec became a symbol of soldierly endurance, especially in comparison with Novogeorgievsk, which a few days earlier had capitulated after a short siege. Among those who fought at Osowiec was also a young sapper second lieutenant, Władysław Strzemiński, later one of the most outstanding Polish avant-garde painters. The ruins of the forts can be seen today in the settlement of Osowiec-Twierdza, on the edge of Biebrza National Park.