BTW:there was no German coup at Danzig,for the reason that Hitler was convinced that such a coup would result in a war with Poland,resulting in a partioning of Poland and this would demand Ribbentrop going to the Kremlin (=going to Canossa) with his hat in his hand .
And,this,Hitler was not prepared to do(later,he changed his attitude).
And,Britain ? It remained at the sideline:there was nothing,it could do,and,there was nothing it had the intention to do ,because ,it was convinced that there was no risk on a war .
Hitler had to choose(and decided):to have Danzig meaned to go to the Kremlin .
The problem with the above interpretation is that it was only at the end of July 1939 that Hitler finally decided to accept the offers being made from the Soviet side.
Indeed, he had earlier ordered Ribbentrop to stop the low-level negotiations with Soviet representatives.
It appears that Hitler chnaged his mind after visiting the West Wall construction site, and realised that it was nowhere near complete and would not be able to stop a French offensive.
The first Soviet approaches about a political settlement between Germany and the Soviet Union were made in April, ie after Poland joined Britain in a mutual military agreement aimed against Germany. However, it was not until the end of July that Hitler decided the accept them.
That suggests that the reason for Hitler's decision to betray his entire political ideology and enter into an agreement with his arch-enemy the Soviet Union was not to get Danzig, since he had been trying for almost a year to get Danzig by an agreement with Poland that was implicitly anti-Soviet.
Hitler was most probably driven by desperation, by his realisation that Britain, France and Poland were gearing up to make war on Germany, and were well on the way to inducing the Soviet Union to join the anti-German coalition.
Remember that in the military discussions in Moscow with the British and French military representatives, the Red Army leaders proposed putting over 100 Soviet divisions into the field against Germany. That was enough of an inducement for Hitler to do anything at all to stop the Soviet Union joining Britain and France, even agreeing to a substantial westward advance of Soviet power, right up to the border of East Prussia.