Osowiec Fortress

The Russians built this fortress at a point where the belt of Biebrza marshes narrows. The railway from Białystok to Ełk and on to Königsberg ran through this gap. The wetlands worked as a natural moat, and the forts sealed the only dry route. In 1915 Osowiec Fortress held out against the Germans for six and a half months, did not fall even after a gas attack, and became famous for the so-called "Attack of the Dead Men".

History: a barrier on the road from Prussia

Tsar Alexander II ordered preparations in 1873, and the main construction took place in 1882–1892. The fortress followed the Russian school of fortification and had four forts: Central (I), Zarzeczny or "Beyond the River" (II), Swedish (III) and New (IV). In the early 20th century it was counted among the most modern fortresses in the world. Fort IV was designed by Nestor Buynitsky, who later fortified Modlin. It was the first and only fort in the Russian Empire cast entirely in concrete.

From January to August 1915 a German corps besieged the fortress with heavy artillery, including 420 mm mortars. When shelling failed, on the morning of 6 August the Germans released a cloud of chlorine and bromine gas. The Russians had no gas masks, and more than 800 defenders died. When the German infantry advanced, a few dozen poisoned soldiers counter-attacked. The sight of them caused panic, and the Germans fell back. The Russians left the fortress only on 23 August, on their commanders' orders, because of the situation along the whole front.

What to see

• Fort I (Central) – the citadel, 2.6 km around, with barracks, shelters and brick details from the brickworks in Hornostaje and Knyszyn. Parts of it can be visited on guided tours.
• The Osowiec Fortress Museum inside Fort I, run by the Osowiec Fortification Society.
• The boardwalk trail – about 2.2 km, largely on walkways across the Biebrza floodplain, with two observation towers, near the ruins of Fort II.
• The red trail – about 2 km through the forest, past three artillery battery shelters and an observation tower on Skobla Hill.

Interesting facts

The counter-attack on 6 August was led by Second Lieutenant Vladimir Kotlinsky and, after he was mortally wounded, by Second Lieutenant Władysław Strzemiński, who later became a leading avant-garde painter. The defence of Osowiec is often compared with Verdun. The memory of 1915 also shaped the next war: in September 1939 the Germans bypassed the fortress and broke through the Polish defences at Wizna instead. In winter the forts' casemates become one of the largest bat roosts in Poland.

Tripto tip

Forts I and III still belong to the army, so Fort I can only be visited on designated routes. The ruins of Fort II are dangerous and should not be explored alone. Osowiec-Twierdza is home to the headquarters of Biebrza National Park, and there is an education centre with observation towers by the railway station. Allow 1–2 hours for the museum and fort, or half a day with the nature trails. Wear sturdy shoes and bring insect repellent, as mosquitoes can be plentiful over the wetlands in summer. In spring the towers are good for watching birds on the floodplain. Check museum visiting times before you travel.