My fathers ship was involved in rounding up the surrendered U-boats - Operation Pledge

Operation Deadlight was agreed between the US, UK and the Russians. Neither side wanted the other to get use of the U-boats, although a lot of them were in bad shape. They agreed to publicly sink them with the press and naval attaches invited to watch.
It all turned into a bit of a fiasco with lots of the U-boats sinking in rough seas.
Also the US secretly sailed one of the advanced U-boats back to the US.

[hargood.weebly.com]