By late September 1918, the German military High Command (OHL), headed by General Erich Ludendorff, had accepted that the Germans could no longer hold the Western Front. Ludendorff hoped that forming a parliamentary government might enable Germany to obtain better terms.
On 1 October, Prince Max of Baden, a liberal, became Chancellor of Germany at the head of a coalition of the Social Democrats, the Catholic Centre Party and the Liberals. On the night of 4-5 October the new government asked US President Woodrow Wilson for an armistice based on his 14 Points. This enabled Ludendorff and other generals to blame the new government for ending the war rather than admitting that the German army had been beaten in the field.
Wilson insisted on 14 October that the Germans must end unrestricted submarine warfare before armistice negotiations began. Admiral Reinhard Scheer, Chief of the German Admiralty Staff, opposed this, arguing that the U-boat campaign against merchant shipping should not be ended until armistice negotiations had begun. On 20 October, however, Prince Max ordered that it should end. This released the U-boats to support operations by the High Seas Fleet, which had been inactive since April.
Scheer ordered Admiral Franz von Hipper, C.-in-C. of the High Seas Fleet to conduct an operation in the North Sea. Hipper’s Plan 19 was to:
- Leave the Helgoland Bight during the day, remaining out of sight of the Dutch coast.
- Destroyers and light cruisers should attack warships in the North Sea and merchant shipping off the Flanders coast and in the Thames Estuary. The High Seas Fleet’s 18 Battleships would cover the operation off Flanders and its five battlecruisers the attack on the Thames.
- This was intended to provoke the British Grand Fleet to leave port and head south. It was by this time based at Rosyth in the Firth of Forth.
- Cruisers and destroyers would lay mines and U-boats wait in ambush in order to reduce the Grand Fleet’s strength as it headed south. About 25 U-boats were to take part and their orders were to take all opportunities to fire on battleships and battlecruisers.
- Hipper planed to engage the Grand Fleet on the night of the second or third day of the operation. If no battle had taken place by then, German destroyers would conduct a sweep towards the Firth of Forth.
Scheer approved the plan on 27 October and it was to be launched on 30 October. The British had a good idea that something major was about to happen because they had detected the movements of U-boats by radio direction finding. The Grand Fleet was reinforced by more destroyers.
The operation did not take place. The High Seas Fleet was ordered to put to sea from Wilhelmshaven on the afternoon of 29 October. A large number of men from the battlecruisers Derfflinger and Von der Tann, mostly stokers, did not return from shore leave that day. There was mutiny and insubordination in other ships as the sailors feared that they were going to be sacrificed in a pointless battle intended only to save the navy’s honour. Hipper called off the operation the next day and dispersed the fleet, which only carried the mutiny to other ports.
Saving the navy’s honour was certainly part of the motivation for the operation. Konteradmiral Adolf von Trotha, Hipper’s Chief of Staff, wrote in a memorandum that:
‘As to a battle for the honour of the fleet in this war, even if it were a death battle, it would be the foundation for a new German fleet of the future if our people were not altogether defeated; such a fleet would be out of the question in the event of a dishonourable peace.’
There were, however, other motivations. In 1667, towards the end of the Second Anglo-Dutch War, the Dutch successfully attacked the Medway, which enable them to get better peace terms than had seemed likely until then.
The Germans would have been outnumbered even more heavily than they had been at Jutland, where their 16 dreadnought battleships and five battlecruisers had faced 28 British dreadnoughts and nine battlecruisers
Wikipedia lists the ships that were likely have taken part in any action. The Grand Fleet had 35 battleships, including five from the USN, and 11 battlecruisers, including two that had only four 15 inch guns and very weak armour, to 18 battleships and 5 battlecruisers. Ten British battleships and five battlecruisers had 15 inch guns and many other Allied ships 14 or 13.5 inch guns, with only the oldest ones having 12 inch guns. Only two German battleships had 15 inch guns, with the others and two of the battlecruisers having 12 inch guns and the three oldest battlecruisers 11 inch guns.
The Germans would be using Zeppelins for aerial reconnaissance, whilst the British had a Flying Squadron of three aircraft carriers and three seaplane carriers. Two of the aircraft carriers. HMS Furious and Vindictive, retained their funnels and superstructures with separate flying off and landing decks. This system created turbulence that made landing difficult. The third, HMS Argus, was the first carrier with a single flight deck running her full length.
At Jutland, the British suffered from lax flash protection and ammunition handling procedures, lack of armour, poor armour piercing shells and an inadequate system for passing intelligence on from the Admiralty to the Grand Fleet’s C.-C. They believed that these problems had been tackled, although Admiral Sir David Beatty, C.-in-C. of the Grand Fleet, thought that the armour protecting magazines was still inadequate.
The British reforms were untested, the U-boats and mines might have inflicted losses as the Grand Fleet advanced and the battle was to be fought near the German bases. The Germans might have repeated their performance at Jutland, when they claimed a tactical victory after sinking more ships than they lost before withdrawing. However, they might also have been annihilated by a fleet that had an even greater numerical and firepower advantage than in 1916 and had corrected many of its faults.
All that can be said for certain about Plan 19 is that if it had led to a battle, American, Australian (the battlecruiser HMAS Australia was then part of the Grand Fleet) , British and German sailors would have died at the end of a war that Germany had already lost.
The fate of the High Seas Fleet was a major concern for the British at the Armistice negotiations, at which the British delegate was the First Sea Lord, Admiral Sir Wester Wemyss. The British wanted to eliminate any future naval threat from Germany. They planned to intern the entire U-boat fleet but feared that the Germans could rebuild it. However, without a German battle fleet the British could have cleared German minefields, carried out a close blockade and destroyed the U-boats close to their bases.
Wemyss therefore wanted the Germans to surrender 10 dreadnoughts, six battlecruisers, eight light cruisers, fifty destroyers and 160 U-boats. The number of dreadnoughts and battlecruisers was intended to leave the Germans with eight or nine, the number that Beatty thought that the Grand Fleet would have lost in a decisive battle that destroyed the High Seas Fleet. 
Some generals and politicians, including Field Marshal Sir Douglas Haig, C.-in-C. of the BEF, Marshal Ferdinand Foch, the French delegate to the Armistice negotiations, and British Prime Minister David Lloyd George, feared that these terms were too harsh and that the Germans might reject them and fight on. Eventually a proposal by Admiral William Benson, the US Chief of Naval Operations, that the German surface ships be interned in a neutral country was accepted. He feared that the British would get the bulk of them if they were surrendered, whilst the British admirals worried that the Germans might get them back if they were interned in a neutral port.
The Germans claimed that they had fewer than 160 U-boats, so Wemyss asked for all their submarines, which was what he really wanted. They had only five battlecruisers as SMS Mackensen was incomplete. The terms signed on 11 November therefore stated that 10 battleships, five battlecruisers, eight light cruisers, 50 destroyers should be interned in a neutral port and all U-boats surrendered. No neutral country was interested in taking the German ships so they were interned in British ports. 
The first group of 20 U-boats left Wilhelmshaven on 18 November. They were met by the Harwich Force of cruisers and destroyers, which them boarded and escorted them into Harwich. Their crews were then transferred to a transport ship, which took them back to Germany. Eventually 176 U-boats were surrendered, including 18 that had been completed in order to make the passage. Seven more sank on the way to Britain.
On 21 November Operation ZZ took place. The Grand Fleet put to sea in order to escort the German surface ships into internment. An Allied force of 370 ships, mainly British but including the American and Australian ships of the Grand Fleet and three French ships, met nine German battleships, five battlecruisers, seven light cruisers and 49 destroyers: a battleship and a light cruiser were in dock and did not come until December and a destroyer struck a mine on the way and sank.
The two forces met at 9:30 am. The Germans the sailed into the Firth of Forth in a single line between two lines each of over 30 battleships, battlecruisers and cruisers. The Allied ships were all at action stations but there was no last minute gesture of defiance by the Germans. The Firth was full of all sorts of vessels carrying civilian spectators. At 11 am Beatty signalled that the German flags should be hauled down at sunset and should not be raised again without permission. This was done at the exact time: 3:57 pm. The German ships were escorted to Scapa Flow on 24 November.
The Germans later scuttled their ships on learning the terms of the Versailles Peace Treaty. This will be described in a later post.
Film of the German surrender from YouTube. You may have to watch an add at the start. The submarines flying British White Ensigns are surrendered U-boats.
 D. Stevenson, 1914-1918: The History of the First World War (London: Allen Lane, 2004), pp. 466-71.
 A. J. Marder, From the Dreadnought to Scapa Flow; the Royal Navy in the Fisher Era, 1904-1919, 5 vols (London: Oxford University Press, 1961-70). vol. v, pp. 170-71.
 P. G. Halpern, A Naval History of World War I (London: UCL Press, 1994), pp. 445-46; Marder, From. vol. v, p. 171
 Marder, From. vol. v, pp. 172-74.
 Quoted in Halpern, Naval, p. 445.
 J. S. Corbett, H. Newbolt, Naval Operations, 5 vols (London: HMSO, 1938). vol. v, p. 369.
 Marder, From. vol. ii. pp. 260-70.
 Ibid. vol. v, pp. 177-78.
 Ibid. vol. v, pp. 177-81,
 Ibid. vol. v, pp. 183-89.
 Corbett, Newbolt, Naval. vol. v, p. 380; R. H. Gibson, M. Prendergast, The German Submarine War, 1914-1918 (London: Constable, 1931), p. 364.
 Marder, From. vol. v, p. 190.
 Ibid. vol. v, pp. 190-92.