A number of years ago I read an investigative report commissioned by the the Weimar Republic to determine the causes of Germany losing World War One. The British Naval Blockade was definitely listed as one of, if not the, major cause for Germany's defeat.

While the blockade was celebrated as a cause of German defeat, I would dispute that. I suspect it is just spin to justify a hugely expensive Royal Navy which was hardly used during the war. The Germans managed to bypass the blockade for years by trading with neutral European countries (like Holland and Sweden). While the Brits pressured the neutrals not to act as a transit point for overseas imports, they continued to trade domestic goods for most of the war. I suspect this trade was actually more of a cause of the German defeat. When the German's ran out of credit to continue this trade with neutrals, they were forced to surrender.

It did not: No more than the war was decided by the tanks at Cambrai or the infantry at the Somme or the artillery at Flanders or the Marines at Belleau Woods. The struggle was certainly winnable by the Germans and Austrians. It was lost, in reality at the failure of the first massive invasion to take Paris...the turn to the south is really the defining moment...the Germans lost sight of their prime objective and it was a battle of attricion of economic from then on...the final outcome was inevitable and quite predictable at that moment considering the freedom of movmenet avaialbe to the allies and the restriction on the Germans...the Kaiser should have insisted on a suit for peace immediately at that failure.

You can bet the neutrals charged a nice premium for this trade forcing the Germans to pay inflated prices for fewer goods. This would mean the blockade forced Germany into bankruptcy and still remains the reason Germany lost.

Take a look at the British blockade policy towards shipping entering nuetral ports. I've heard they were strictly limiting what the Dutch could import.

Looking at your premise....well when the Germans ran out of credit they couldn't go elsewhere, why? Because of the blockade.

A related question. General it is accpted that Blockade severally effected German war capacity in WW1. So, why it did not effect German war efforts in the WW2.

Maybe it did. Take a look at how restricted imports of critcal items like rubber and rare metals for alloys, or diamonds. I'd recomend 'Brute Force' by Ellis as a start to understanding Germanys industrial position in WWII. The effect is not so obvious as the isolation was not effective until 1942. Italy was a nuetral conduit for critical imports until June 1940. Food & rare items came through the USSR until June 1941. Spain and Turkey resisted restrictions at least through 1942, probably longer. Germany also looted the areas it conquored. Germans did not suffer from malnutrition because the French, Dutch, Belgians, Serbs, Urkranians, ect... were deprived of rations. Similarly the Nazis confisticated any industrial items they needed. In WWI the blockade became complete in 1915, after Italy declared for the Allies and the Scandinavians & Dutch gave in to British pressure. In WWII it became effective from late 1942. In both cases it took about two years to cause severe problems in Germany.

A relevent question might be, "For wars which are not over quickly, does sea power count now as much as in the past (The first and second Punic wars, the American War Between the States, the Seven Years War/French and Indian War, WWI, etc)?"

>> A relevent question might be, "For wars which are not over quickly, does sea power count now as much as in the past (The first and second Punic wars, the American War Between the States, the Seven Years War/French and Indian War, WWI, etc)?" << In an economy which has adopted "just in time" inventory supply (which is the world standard right now) sea blockades would become critical in a matter of weeks, months at most.