At the outbreak of World War I in August 1914, Brandenburg was reactivated and assigned to V Squadron, which was initially tasked with coastal defense duties in the North Sea.
In mid-September, V Squadron was transferred to the Baltic, under the command of Prince Henry.
He initially planned to launch a major amphibious assault on Windau, but a shortage of transports forced a revision of the plan.
Instead, V Squadron was to carry the landing force, but this too was cancelled after Heinrich received false reports of British warships having entered the Baltic on 25 September.
Brandenburg and the rest of the squadron returned to Kiel the following day, disembarked the landing force, and then proceeded to the North Sea, where they resumed guard ship duties.
Before the end of the year, V Squadron was once again transferred to the Baltic.
Prince Henry next ordered a foray toward Gotland.
On 26 December, the battleships rendezvoused with the Baltic cruiser division in the Bay of Pomerania and then departed on the sortie.
Two days later, the fleet arrived off Gotland to show the German flag, and was back in Kiel by 30 December.

The squadron returned to the North Sea for guard duties, but was withdrawn from front-line service in February 1915.
Shortages of trained crews in the High Seas Fleet, coupled with the risk of operating older ships in wartime, necessitated the deactivation of the V Squadron ships.
Brandenburg had her crew reduced in Kiel, and she was briefly assigned to the reserve division in the Baltic.
From July to December, she underwent shipyard maintenance, before being transferred to Libau.
On 20 December, she was decommissioned there, for use as a water distillation and barracks ship.
Her heavy guns were removed for use in the Ottoman Empire, but there is no record of them ever having been shipped to the Ottomans.
Near the end of the war, Brandenburg was taken back to Danzig, where work began to convert her into a target ship, but the war ended before the reconstruction was completed.
Brandenburg was struck from the naval register on 13 May 1919 and sold for scrapping.
The ship was purchased by Norddeutsche Tiefbaugesellschaft, a shipbreaking firm headquartered in Berlin, and she was then broken up for scrap in Danzig.
At the outbreak of World War I in August 1914, Brandenburg was reactivated and assigned to V Squadron, which was initially tasked with coastal defense duties in the North Sea. In mid-September, V Squadron was transferred to the Baltic, under the command of Prince Henry. He initially planned to launch a major amphibious assault on Windau, but a shortage of transports forced a revision of the plan. Instead, V Squadron was to carry the landing force, but this too was cancelled after Heinrich received false reports of British warships having entered the Baltic on 25 September. Brandenburg and the rest of the squadron returned to Kiel the following day, disembarked the landing force, and then proceeded to the North Sea, where they resumed guard ship duties. Before the end of the year, V Squadron was once again transferred to the Baltic. Prince Henry next ordered a foray toward Gotland. On 26 December, the battleships rendezvoused with the Baltic cruiser division in the Bay of Pomerania and then departed on the sortie. Two days later, the fleet arrived off Gotland to show the German flag, and was back in Kiel by 30 December.
The squadron returned to the North Sea for guard duties, but was withdrawn from front-line service in February 1915. Shortages of trained crews in the High Seas Fleet, coupled with the risk of operating older ships in wartime, necessitated the deactivation of the V Squadron ships. Brandenburg had her crew reduced in Kiel, and she was briefly assigned to the reserve division in the Baltic. From July to December, she underwent shipyard maintenance, before being transferred to Libau. On 20 December, she was decommissioned there, for use as a water distillation and barracks ship. Her heavy guns were removed for use in the Ottoman Empire, but there is no record of them ever having been shipped to the Ottomans. Near the end of the war, Brandenburg was taken back to Danzig, where work began to convert her into a target ship, but the war ended before the reconstruction was completed. Brandenburg was struck from the naval register on 13 May 1919 and sold for scrapping. The ship was purchased by Norddeutsche Tiefbaugesellschaft, a shipbreaking firm headquartered in Berlin, and she was then broken up for scrap in Danzig.
SMS Brandenburg