After entering service, the Nassau-class ships served as II Division, I Battle Squadron of the High Seas Fleet for the duration of their careers.

These frequently consisted of sailing as distant support to the battlecruisers of I Scouting Group as they raided British coastal towns.

These operations culminated in the Battle of Jutland on 31 May – 1 June 1916, where the ships helped to sink the armored cruiser HMS Black Prince.

Though the Nassau class is commonly cited as a response to the revolutionary HMS Dreadnought,[1] the decision to adopt an all-big-gun main battery predated the construction of the British vessel.

Kaiser Wilhelm II argued that the navy ought to build large armored cruisers as a single capital ship type.

[3] During deliberations in late April, "Project I" emerged as the favored design since it would be cheaper than "II" (which would also require widening of the Kaiser Wilhelm Canal).

The Kaiser again attempted to meddle in the design process after he learned of the Italian Regina Elena-class battleships, which were capable of 22 knots (41 km/h; 25 mph); he pressed the navy to build a similar vessel, along the same lines as the type he had suggested in 1903.

Admiral Alfred von Tirpitz pointed out that merging the battleship and armored cruiser categories would not be possible under the Naval Law of 1900, and that the Construction Office was too busy with other projects to take on another one.

[4] During this period, Tirpitz worked to secure the passage of the next Naval Law; he had originally requested six new battleships and six armored cruisers, along with a number of miscellaneous smaller craft.

Funds were also provided to widen the Kaiser Wilhelm Canal and enlarge dock facilities to accommodate the larger ships.

Internal rearrangements to the magazines and boiler rooms resulted in "G2", while an attempt to move all of the gun turrets to the broadside was presented as "G3", but this proved to be unworkable.

[8] The heavy wing turrets caused the ships to have a large metacentric height, which should have made them very stable gun platforms, but their roll period proved to coincide with that of the average North Sea swell.

The propulsion system was rated at 22,000 metric horsepower (22,000 ihp) for a top speed of 19 knots (35 km/h; 22 mph), though in service, all four ships exceeded these figures by a wide margin.

[7] The basic armor layout divided the ships into three sections: the bow, the stern, and the central citadel, the latter extending from the fore to the aft main battery barbette.

Each year typically culminated in a summer training cruise in July, frequently to Norwegian waters, followed by the annual fleet maneuvers held in late August and early September.

The one exception to this was 1912, when the summer training cruise remained in the Baltic Sea owing to increased tensions with Britain and France as a result of the Agadir Crisis.

The ships were in Norway during the July Crisis in 1914 and were hastily recalled to begin the mobilization for war when it became apparent that conflict between Austria-Hungary and Serbia would not be avoided.

The first of these was the raid on Yarmouth on 2–3 November 1914, which was conducted by the battlecruisers of Konteradmiral (KAdm—Rear Admiral) Franz von Hipper's I Scouting Group while the battleships provided distant support.

The Nassaus and the rest of the fleet got underway to relieve the battlecruisers after they were ambushed in the Battle of Dogger Bank on 24 January 1915, but they arrived too late to intervene.

The Russian Baltic Fleet had stationed the pre-dreadnought Slava and a number of gunboats and destroyers in the gulf, the entrances to which were protected by a series of minefields.

[32] After returning to the North Sea, the fleet conducted another sortie in the hope of catching a British squadron in October, with further operations beginning in March 1916, now under the direction of VAdm Reinhard Scheer.

With the ability to decode German wireless signals, they could send forces to attack the High Seas Fleet under conditions favorable to themselves, as they had done at Dogger Bank.

[36] The initial phase of the action, which began at 16:00 on 31 May, consisted of a running battle between the opposing battlecruiser squadrons as Hipper lured the British commander, Vice Admiral David Beatty, south toward Scheer's fleet.

At 18:55, Scheer decided to conduct another 16-point turn to launch an attack on the British fleet but was quickly forced to break off and withdraw.

Nassau and Ostfriesland joined in, followed by Friedrich der Grosse; the combined weight of fire destroyed Black Prince in a tremendous explosion.

Following the return to German waters, Nassau, Posen, and Westfalen, along with the Helgoland-class battleships Helgoland and Thüringen, took up defensive positions in the Jade roadstead for the night, while Rheinland refueled and rearmed.

[43] Less than three months after Jutland, Scheer embarked on another operation in the North Sea; in the resulting action of 19 August 1916, Westfalen was torpedoed by the British submarine HMS E23, but suffered minimal damage and was soon repaired.

While the bulk of the fleet conducted Operation Albion in the Gulf of Riga in October 1917, the four Nassaus patrolled the eastern Baltic to block a potential British incursion to support Russia.

The Germans had mistaken intelligence about the timing of the convoys, however, and failed to intercept one when they sortied in April 1918; Nassau was the only member of the class to take part in the operation.

[48] Following the end of the First World War in 1918, eleven battleships of the König, Kaiser, and Bayern classes and all five battlecruisers, along with a number of light cruisers and destroyers, were interned in Scapa Flow, while their fate was determined in the negotiations over the Treaty of Versailles.