It’s all in the book I mentioned. It was intended for Germany because the US thought the Germans had an active nuclear program. Even Japan had one as well. It’s not that the US had an active A-bomb at the time but the development was aimed at Germany first.
“It was intended for Germany”
It was never intended at Germany. Trinity wasn’t until July of that year. Until Trinity they had no clue that the bomb would actually work - they had tested and failed.