Bartemius Crouch Senior was regretful.
For the past 20 years, he believed that his Wizarding War policies were good, and needed.
First, he convicted several suspected criminals to life imprisonment in Azkaban. Next, he allowed Aurors to use Unforgivable Curses on Death Eaters and sympathizers. That got him the job as Minister of Magic, and his reign of terror went unchecked.
He authorized civilians to use the Killing Curse on suspected Death Eaters. Next, he authorized magical spying on the population of Magical Britain. Suspected pro-Voldermort newspapers were shut down and investigated thoroughly. Hundreds of people were murdered by their friends, family, colleagues and Aurors who suspected them for being Death Eaters.
In the end, the Dark Lord himself was killed. And then Crouch was shocked by the identities of the last remaining Death Eaters.
Bartemius Crouch Senior put flowers on the grave of Bartemius Crouch Junior, killed by Aurors.