| Conflict: | Battle of Åland Islands |
| Partof: | World War I |
| Place: | off Gotland, Sweden near Åland |
| Result: | Entente victory |
| Combatant1: | |
| Combatant2: | |
| Commander1: | Johannes von Karpf |
| Commander2: | Mikhail Bakhirev |
| Strength1: | 3 armored cruisers 1 cruiser 2 light cruisers 7 torpedo boats |
| Strength2: | 3 armored cruisers 2 light cruisers 1 destroyer 1 submarine |
| Casualties1: | 2 armored cruisers damaged 1 cruiser grounded 27 dead and 49 wounded |
| Casualties2: | Minor damages |
The Battle of Åland Islands, or the Battle of Gotland, which occurred in July 1915, was a naval battle of World War I between the German Empire and the Russian Empire, assisted by a submarine of the British Baltic Flotilla. It took place in the Baltic Sea off the shores of Gotland, Sweden, a country neutral in World War I.
On,[1] a squadron consisting of the armoured cruisers,,,, and, under Rear Admiral Mikhail Bakhirev in Oleg left their harbours in order to bombard Klaipeda (Memel). While sailing through thick fog Rurik and Novik separated from the main group and later acted independently.[2]
On the same day the German mine-laying cruiser, screened by the armoured cruiser, the light cruisers and, and seven destroyers, under Kommodore Johannes von Karpf, was laying mines off the Åland Islands. After completing his mission, Karpf reported back through the radio. Karpf's message was intercepted and decoded. When Bakhirev became aware of the German squadron's whereabouts, the bombardment of Klaipeda was canceled. The squadron then focused on intercepting the German minelayers with the constant assistance of the naval staff.[2]
In the early morning of, the Russian squadron spotted and immediately opened fire on Augsburg, Albatross and three torpedo boats. Karpf commanded Roon and Lübeck, which at the time were heading towards Liepāja (Libau), to return to Gotland. At the same time he ordered Albatross to find shelter in Swedish territorial waters. Bogatyr and Oleg managed to catch up with Albatross and opened fire. The flaming Albatross ran aground near Östergarn. Bayan, Oleg and Rurik then attempted to return to their base. A couple of hours later they encountered Roon and Lübeck. A short artillery duel followed. A shortage of shells forced the Russian cruisers to retreat. Fearing a possible arrival of enemy reinforcements the damaged German ships also retreated.[2]
As the German armoured cruisers and sailed to reinforce the German squadron, Prinz Adalbert was torpedoed by the British submarine and limped to shore.[3]
The battle is regarded as the first instance of Russian signals intelligence.[4]