Where they got them before. In WW2 transport wasn’t just by US or allied flagged ships. These were civilian ships chartered for particular voyages. A ship sailing into dangerous waters would be required to sail in a convoy.
” In WW2 transport wasn’t just by US or allied flagged ships. These were civilian ships chartered for particular voyages. “
What I see for the Newf /NY - UK convoys is that the convoy ships were overwhelmingly UK or USA.
https://warsailors.com/convoys/hxconvoys6.html
Which means the lack of domestic owned/flagged ships is yet another huge strategic hole that “Outsourcing” has dug for us.