ENT -- Last bunch of EPs [SPOILERS] - The schedule was posted on Trek Today

[Derek]

[color=#000000ost_uid0][quoteost_uid0="PointyHairedJedi"]I'm just making the point that the war had more effect than just "a relatively unimportant Picard line", including the various episodes connected with the [iost_uid0]Enterprise-C[/iost_uid0].[/quoteost_uid0]
Actually, we should go back to the first appearance of the Klingons, which is TOS's "Errand of Mercy". In it we hear that relations with the Klingons were "breaking down", suggesting that they had some sort of peace or something. Based on that my understand of canon (excluding ENT for now) is:

Bad FC with Klingons, results in war
Fragile peace is reached at some point.
In "Errand of Mercy" (TOS) peace breaks down and species are hostile to each other.
In "The Enterprise Incident" (TOS) we learn that the Romulans and Klingons seem to be pals.
Romulans and Klingons obviously break up at some point.
Klingons and Federation bring some of their hostilities to an end in ST6 leading to some sort of understanding.
Presumably the Federation and Klingons become allies at some point after the ENT-C incident.
The treaty is dissolved during DS9's run, and later renewed also during its run.[/colorost_uid0]