- I think a serious reverse for the Royal Navy would have massive follow-on effects, not minimal ones. There would be immediate, pressing concern over food and raw materials supplies for the home islands, real fear of invasion and an urgent need to build a lot of new warships, quickly. All of that means resources diverted from the army in France, which basically spells retreat or at the very least the end of offensive action. Longer, exposed supply routes to France, coupled with the issues of trans-shipping by railroad from Brest, Le Havre or Bordeaux to Flanders, would force the Royal Navy to use capital ships to escort troop and supply convoys. The French ports would be overburdened, the railroads would be overloaded and, given the Royal Navy's inability to promise security for its supplies, the British Army might try to evacuate Flanders. And not incidentally the use of heavy units for convoy escort in the south opens up the North Sea exits in the North for German raiders and blockade runners. The threats of invasion, convoy destruction and so forth do not have to happen, they only have to be seriously credible for Britain to have to take immediate, drastic steps, and every effort they make will benefit Germany.
This may all sound alarmist and overblown, but the Royal Navy sweated blood in 1914 over getting the BEF safely to France, and the French transport network (including ports and railroads) were heavily overstrained by war imports. Adding distance to shipping increases the amount of shipping required and delays delivery - this, coupled with invasion scares (the fear would be real whether the invasion was a credible threat or not) and a massive shift in resources from the Army back to the Navy, would curtail - perhaps end - the Army's scope of action. Remember that the BEF went to Flanders principally because that was where it could be most securely and easily supplied. If the Channel ports aren't usable, the Home Islands are threatened and supplies and reinforcements are in doubt then what does the BEF do? Ask France to pick up the slack?
I agree with a lot of these points, but there are other things which need to be considered. Let us suppose that the Germans achieve a great victory over the Royal Navy and shatter its Battleship fleet and its ability to maintain supreme control over the North Sea and German ability to sail into the Atlantic.
The first point to consider is that the UK was in no way as dependent as Germany on the import of many goods. The UK did import many grain products from overseas it was was more productive than Germany in terms general agriculture
For example Britain was both more productive despite being a smaller nation in terms of many sectors, the most important of which are agriculture are probably those of agriculture and construction (where the UK was more productive). What was actually seen in the UK was that agriculture had shifted with imports focusing on grain, wheat and potatoes and home production focusing on meats and dairy produce. There is already historical precedence for the UK agriculture sector being able to absorb a drop in imports in this sector - in 1916 the US harvest was particularly poor, yet by 1918 UK home production of grains and potatoes had grown by around 1/3 while the meat/dairy had shrunk by a proportional amount [1,2]. That is, the UK was more robustly able to absorb changes in world markets and import situations.
Now, lets entertain the idea that Germany forces on the RN a defeat which reverses the situation ... that is the Grand Fleet does not leave its harbors for the remainder of the war. Would Germany be able to impose a blockade of similar severeness as the UK? Probably not - in the first instance, the UK was able to blockade at range, closing the north sea and English Channel, where all of the German import docks were established along a single coast. To do so, Germany would have to close off the entire Atlantic something that would be logistically a challenge and would force German forces to 'disperse' their strength - that is, battleships/cruisers acting in isolation could be forced to fight strategically disadvantaged actions. So yes, Germany could have an effect, but no they would not cut off trade as completely as the UK was able to.
The other consideration is that the German fleet wasn't really a High Seas fleet ... it was a North Sea Fleet. The ships were principally coal powered and given that Germany had no overseas bases from which to conduct coaling operations, their forrays into the Atlantic would have been relatively short, before they need to sail back to Germany and re-load. That is, sailing into the middle of the Atlantic already uses about 1/3 of their sailing range.
The idea that Germany might disrupt shipping in the English Channel is also a little erroneous. There was one of the worlds largest destroyer fleets stationed in the channel (Dover I think) and were highly effective at engaging battleships (with Torpedos) in constrained waters. The German destroyer torpedo volley was one of the things which helped to cover the German high seas fleet as it disengaged.
[1] THE UNITED KINGDOM DURING WORLD WAR I: BUSINESS AS USUAL? Stephen Broadberry 2003.
[1] “Anglo-German Productivity Differences, 1870-1990: A Sectoral Analysis”, European Review of Economic History 1, 247-267.
I do think a German 'win' would be fleeting - the Royal Navy still would have a lot of assets and it would have 'blood in its eye and murder in its heart'. And it is easier to challenge for sea supremacy than to keep it... if the High Seas Fleet tried to capitalize on its success with further ambitious operations in the North Sea it might find itself 'foxed' in turn. But however that turned out, the aftermath of a German win at Jutland would be very bad for the Allies, especially so given that the operation's historical failure led to the resumption of unrestricted submarine warfare by Germany and the entry of the United States into the war on the Allied side.
I think that this is the crux - a German victory would be bad, but not the end of allied operations. The high seas fleet was actually a North Seas fleet. Germany did not have the overseas logistics to sustain such a world-wide fleet as the Anglo-Americans operated. Even if they win, they gain superiority in the North Seas but struggle to projec their power anywhere that would have a decisive impact.
