For those of you paying attention to the Cascadian History posts in the History Thread, lack of detailed history among everyone else has me leery of adding too much detail.
Basically Cascadia, in the 19th Century, established an enclave/colony on the big Untamed Continent, aka Velestria, that was known as New Olympia. Depending on if they're PCs or not, either the blue or purple island to the west of MESSamerica also had a Cascadian naval post and possible small colonial region.
Sometime in 1916, given WW1 was raging in at least the Old Continent, there was a brief warscare that led to a general strike in Seattle, Vancouver, and a couple other cities, fomented by Socialist agitators opposed to Cascadian military action.
Years later, in World War II, Cascadia aligned with the Allies, probably a benevolent neutral at first and becoming a belligerent over time. Aside from a potential colonial campaign in Velestria or the nearby islands, my concept was that Cascadia's main effort in the war ended up being a contribution of troops to the fighting on the Impact Crater Continent, joining Allied/MESS forces in offensives/counteroffensives that forced Shepistan to the negotiating table (the Cascadian military contribution was likely a full Army formation, which I figure is realistic given that Canada managed to field the 1st Canadian Army in Europe in 1944-1945), centerpieced by the full Cascadian Republic Guard Corps.
This was the point in history when Cascadia may have joined the MESS alliance. But that possibility was eliminated by the post-war treaty settlements, when Cascadian interests in Velestria and the Pacific (Western) Ocean islands between Velestria and MESSamerica were mostly ignored in the treaty arrangements. Though Cascadia got some terms,the Republic was not given everything it desired from the arrangements (not unsurprising; Lonestar for one, I think it was him anyway, gave the idea that the MESS powers may have very well seen little reason to give Cascadia some of what it wanted if it hadn't entered the war at an earlier time or contributed very much until late) and so it soured on the initial considerations of aligning with MESS.
In the years since Cascadia granted New Olympia independence (as well as the island colony enclave if it ahd one), likely in the same timeframe that the other empires of the civilized world gave up on their possessions in Velestria and Frequesue, though it maintains its own economic influences in Velestria and the islands of the Pacific. Cascadia, due to those interests and influence, has maintained a decent Navy that has waxed and waned in capability over the years, though it has now recovered under supportive government programs that have given it two aircraft carriers and amphibious operations capability (the carriers are non-nuclear versions of France's
Charles de Gaulle, which have some amphibious assault capability, and the Cascadian Navy has LPDs as well).
Relations with the rest of the world are cordial, mostly. Tian Xia remains relatively friendly, if relations are sometimes distance and cool in their cordiality, though there is always the potential for some niggling thing to provoke a round of diplomatic fussing. The Shinra Republic is a close friend of Cascadia and the two nations enjoy considerable trade links as well as joint projects of economic, scientific, and even military value (Cascadia is a junior partner in the Joint Strike Fighter program and will receive an initial order of eight F-35Cs for its carrier fleet as they are made available). Alaska is, I believe I arranged with Marius, an old trading partner that Cascadia enjoys decent relations with, and there may even be some joint navy operations revolving around ocean Search-and-Rescue missions. Relations with Wilkonia may be slightly more distance due to lack of a common border, but unless there is overlap in our oceanic interests I see no reason for anything but a friendly relationship. We probably maintain cordial relations with most other countries save Astaria, Japanistan, and Shepistan. Hell, we probably don't even mind engaging in trade links with those damned dirty Commies of the Crimson Star Republic.

(Stas -

).
Current tension points are probably only in keeping things quiet in Velestria, where the carriers are typically deployed to when they're not in the home waters, and participation in the ongoing three-way dispute with Alaska and Tian Xia over fishing rights and economic use of the waters in the extreme northeast Pacific.