The phrase "accomplished fact" refers to something that has already been done or achieved, and cannot be changed or undone. It is used to describe a situation that is considered final and certain. Full definition
It began as an idea that one or the other had and became accomplished fact without planning. (bookbrowse.com)
When someone obeys God by faith, he is obeying — doing good works — not because he seeks merit but because he believes God's word and promises as accomplished facts. (redeeminggod.com)
They are wrong, of course; world opinion respects accomplished facts and power, both of which are now ranged on Israel's side. (religion-online.org)