What did the Germans pledge they would do to any Allied vessel sailing around Britain?

The correct answer is provide warning before shooting

Germany had the largest submarine fleet among the belligerent countries. However, the commanders of these vessels had been refraining from torpedoing passenger ships (albeit with an enemy flag) and any ships from neutral countries. The exception was the English transatlantic Lusitania, torpedoed in 1915 and which exploded - probably because it was secretly transporting American ammunition to England.

In January 1917, the German government announced that it would launch an “unrestricted” underwater campaign; that is, their submarines would torpedo any ships trying to reach French or British ports. This decision complicated the situation of the Allies, since Great Britain depended on sea supplies for its own survival.

In March 1917, the Russian Revolution broke out. Tsar Nicholas II was overthrown and a liberal provisional government (formed by aristocrats and bourgeois) took over. Officially, Russia continued in the war against Germany; but his soldiers, exhausted and demoralized, practically stopped fighting. This circumstance could allow the Germans to deploy troops to the western front, definitively defeating the English and the French.

In the course of the war, the United States had become a major supplier to the Allies, to which it sold everything from food to weapons and ammunition. Great Britain, France and other countries had accumulated enormous debts with American businessmen, who could not bear the fantastic loss resulting from a possible Anglo-French defeat.

the underground railroad (apocope of the metropolitan railroad) is a system of urban trains located within a city and its metropolitan area. it is characterized for being a massive transport of passengers in the big cities, uniting diverse zones and their environs, with high capacity and frequency and in segregated form to other systems of transport. metropolitan railroads are built underground or on the surface, although most systems use mixed models where sections are combined in both modalities.

1 - as a result, the metro tends to reduce car travel for two reasons: first, due to the greater transfer of users from the car and, second, due to the reduction in the acquisition of cars in homes located in sectors near the stations of the metro.

2 -the metro allows to contribute effectively to the achievement of all the objectives of an urban development policy: it improves the efficiency of the city's economy by reducing travel costs and also generates a higher level of activities in the city center, taking advantage of of the agglomeration economies.

3 -it is a clean means of transport, since it uses renewable energy (usually electricity), taking care of the environment and avoiding excessive pollution.