Location: N57° 2` 45.15", E24° 2` 21.48"
Daugavgrīva stronghold is a 17th century stronghold on the angle of the left coast of Daugava. This angle is created by Lielupe embouchure in Daugava with its left coast, where much older Daugavgrīva ruins were standing.
The origins of the Daugavgrīva stronghold can be found in 17th century when Swedish army built their first fortifications on the new Daugava creek in 1608 during the Polish-Swedish war, and settled a garrison of 250 men there. In 1609 Lithuanian captain Chodkiewicz invaded recently built stronghold, but Swedish fleet arrived in Daugava creek on August of 1617 and recovered Neiminde fortification. Neiminde fortification was invaded by Riga City army in 12.-14 September, 1617. Swedish fleet with 150 ships disembarked commandoes on Daugava creek in 13th August, 1621, and after a long lasting bombing both Daugavgrīva stronghold and Neiminde fortification defenders surrendered on the 2nd of October. In 1670 Swedes updated the stronghold after that time standards, following marshal Vauban updates in fortification. The five initial bastions were expanded, the sixth bastion, new casemates and powder basements were built, ramparts were made and the ditches were dug deeper.
At the beginning of the Great Northern war, Saxon army led by General Fleming was crossing the frozen river to attack Daugavrgīva stronghold on night of the 24th March, 1700. The Swedish garrison of 500 men repelled the attack, and it is thought that around 1000 Saxon soldiers fell that night. As Swedish garrison had to fight against 6 Saxon battalions and the ice on Daugava and Lielupe allowed the attack from any side, stronghold was council decided to surrender. On 28th of March Swedes left the stronghold taking all their ammunition with them, but Fleming renamed the stronghold in honour of King August II – Augustburg.
On 1701 the stronghold was surrounded by 500 infantrymen and 120 riders led by Swedish colonel Albedil, and on 23rd of December the stronghold went back on Swedish hands. On 26th of November, 1709, Russian Emperor Pether I started the 9 month long Riga blockade. Swedes had 10000 large garrison in Riga and 1000 men garrison in Daugavgrīva. The stronghold finally surrendered in August, 1710. In 1710 it consisted of 6 bastion fronts with water ditches, stone scarps and covered passage. Barracks and powder basements were located inside.
In 1755 Russian Empire army built new stronghold church and in 1765 started to build so called comet fort.
In 1850 outline for Mangaļsala dam was laid to avoid further lodgement of Daugava creek, and a telegraph line was installed in stronghold in 1852. A bridge over Buļļupe was built on 1858 and a railway line to Riga was opened in 1871. It was renamed Ustjdvinska stronghold during the period of Baltic’s russification in 1893.
At the beginning of the WW I in 1915, about 9 500-10 000 men were located in stronghold, but on 16th August, 1915, 1. Daugavgrīva Latvian Riflemen battalion was starting to form. Although siege state in stronghold was announced already from 1914, the only forces it had to turn the weapons at were enemy zeppelins and aeroplanes. To cover receding Russian army parts during Riga operation on 2nd of September, 1917, stronghold batteries opened fire towards Sloka, approximately 16km until Majori and Jelgava motorway. Later artillerists and field engineers blew up the batteries, canons, burned down buildings and things, and in German hands this stronghold was already in completely unusable state.
LSPR army was situated in Daugavgrīva stronghold from 3. January to 22. May, 1919, but later it was invaded by landeswehr. During Bermondt fight in 13th October, 1919, Great Britain and France warships sailed from Daugava and anchored in the sea in front of Daugava creek. When Latvian army planned to force Daugava, general Simanson asked the ally fleet artillery support from Daugavgrīva side on 14th October, and on 15th October the ally fleet opened fire. After intensive shooting the 9th Rēzekne infantryman squadron rowed across Daugava and occupied Bolderāja and Daugavgrīva stronghold, where around 300 Bermondt army solders surrendered. After the war of Latvia independence the stronghold was given to Latvian army artillery squadron.
After occupation of Latvia in 1940 it was occupied by USSR Baltic war fleet unit who located USSR military garrison there.