SMS Seydlitz followed by Derfflinger-class battlecruiser
Battle of Dogger Bank
In early January 1915, it became known that British ships were conducting reconnaissance in the Dogger Bank area. Ingenohl was initially reluctant to attempt to destroy these forces, because I Scouting Group was temporarily weakened while Von der Tann was in drydock for periodic maintenance. Konteradmiral Richard Eckermann, the Chief of Staff of the High Seas Fleet, insisted on the operation, and so Ingenohl relented and ordered Hipper to take his battlecruisers to the Dogger Bank. On 23 January, Hipper sortied, with Seydlitz in the lead, followed by Moltke, Derfflinger, and Blücher, along with the light cruisers Graudenz, Rostock, Stralsund, and Kolberg and 19 torpedo boats from V Flotilla and II and XVIII Half-Flotillas. Graudenz and Stralsund were assigned to the forward screen, while Kolberg and Rostock were assigned to the starboard and port, respectively. Each light cruiser had a half-flotilla of torpedo boats attached.Again, interception and decryption of German wireless signals played an important role. Although they were unaware of the exact plans, the cryptographers of Room 40 were able to deduce that Hipper would be conducting an operation in the Dogger Bank area. To counter it, Beatty's 1st Battlecruiser Squadron, Rear Admiral Archibald Moore's 2nd Battlecruiser Squadron and Commodore William Goodenough's 2nd Light Cruiser Squadron were to rendezvous with Commodore Reginald Tyrwhitt's Harwich Force at 8:00 on 24 January, approximately 30 nmi (56 km) north of the Dogger Bank. At 08:14, Kolberg spotted the light cruiser Aurora and several destroyers from the Harwich Force. Aurora challenged Kolberg with a search light, at which point Kolberg attacked Aurora and scored two hits. Aurora returned fire and scored two hits on Kolberg in retaliation. Hipper immediately turned his battlecruisers towards the gunfire, when, almost simultaneously, Stralsund spotted a large amount of smoke to the northwest of her position. This was identified as a number of large British warships steaming towards Hipper's ships.Hipper turned south to flee, but was limited to 23 knots (43 km/h), which was the maximum speed of the older armored cruiser Blücher. The pursuing British battlecruisers were steaming at 27 knots (50 km/h), and quickly caught up to the German ships. At 09:52, Lion opened fire on Blücher from a range of approximately 20,000 yards (18,000 m); shortly thereafter, Queen Mary and Tiger began firing as well. At 10:09, the British guns made their first hit on Blücher. Two minutes later, the German ships began returning fire, primarily concentrating on Lion, from a range of 18,000 yards (16,000 m). At 10:28, Lion was struck on the waterline, which tore a hole in the side of the ship and flooded a coal bunker. At 10:30, New Zealand, the fourth ship in Beatty's line, came within range of Blücher and opened fire. By 10:35, the range had closed to 17,500 yards (16,000 m), at which point the entire German line was within the effective range of the British ships. Beatty ordered his battlecruisers to engage their German counterparts. Confusion aboard Tiger led the captain to believe he was to fire on Seydlitz, which left Moltke able to fire without distraction.
Seydlitz was struck in her forecastle at 10:25, by a 13.5 in (343 mm) shell from Lion, but this hit did minor damage. At 10:40, Lion hit Seydlitz with another 13.5 in shell, which holed the deck and penetrated the rear barbette. The shell itself failed to enter the barbette, but the explosion flashed into the working chamber and detonated the propellant charges inside.