Bulgaria, who was not affected by this phase of the war, and had kept up diplomatic relations with America, was differently situated, being able to stand aside without paralysing the German plans.

Apart from this, I was already persuaded then that Bulgaria's not joining in would make a bad impression on the outside world, and would not help her in any way.

Although her relations with America were maintained up to the last, they did not, as a matter of fact, make her fate easier.
Had we been able to make Germany desist from the unrestricted U-boat warfare, the advantage would have been very great; whether we joined in or not was a matter of indifference viewed from the standpoint of our treatment by the Entente, as is proved by the instance of Bulgaria.

As soon as America had declared war on Germany, a conflict with us was inevitable in any case, as Austro-Hungarian troops and artillery were then on the Western front facing Americans.

We were compelled to go to war with America, seeing that Germany was already at war with her.
It was not possible, therefore, for us to remain in a state of even nominally peaceful relations with America, such as existed between her and Bulgaria to the very end of the war.
It is not quite clear when Germany really recognised the fact that the unrestricted U-boat warfare had no effect, and was thus a terrible mistake.