That's pretty much what happened in Northern Ireland as part of the Good Friday Agreement:
https://en.wikipedia.org/wiki/Police_Service_of_Northern_Ire...
https://en.wikipedia.org/wiki/Police_Service_of_Northern_Ire...
Worst year of Troubles: 1972, 479 troubles-related deaths. I'm unclear as to whether that includes "background" non-political crime, so I'll round it up to 500 (current NI murder rate is about 1/100k pop).
Current Baltimore murder rate: 373 in 2017.
Murder rate for three Baltimores: 1119.
That makes today's Baltimore twice as lethal as Troubles NI, with all its carbombs and troops on the streets.
It's a mess that to me would seem to warrant national intervention. https://www.economist.com/news/united-states/21724399-americ...
edit: add a dodgy esimation
Belfast poulation in 70's: 431k
% of troubles deaths in Belfast : 43%
=> murder rate: 479 * 0.43 / 431 = 44 homicides per 100k
But as you note, the NI figures is only the political murders so it can only really be compared against a similar subset of Baltimore homicides e.g. "gang violence".