The war, however, soon proves no more than a matter of small-scale skirmishes, because the nations of Europe, bloodied by World War I less than a decade earlier, simply don't have the manpower to fight any sort of global warfare, while America's navy cannot manage cross-oceanic operation against the might of the Royal and Imperial Japanese Navies.
Moreoever, many participants drop out of the war almost as soon as it begins. America is among the first, following the election of Democrat Al Smith to replace Coolidge (the Republicans fails to get more than a single state's support), after a 1928 electoral campaign largely based on the war. Smith rapidly conclude several peace treaties.
Similarly, in Canada, an armed Loyalist uprising in Ontario rapidly force William Lyon Mackenzie King to withdraw his country from the war. He is nonetheless jailed, and later tried and executed on charges of high treason, Canada being still a Dominion of Great Britain, and many English-Canadians feeling highly loyal to the Crown. Many of the "traitors" flee to Québec, where they are hidden among the french community. Repression against french-Canadian begins anew.
The other American nation, being powerless to intervene without any sort of navy, effectively drift out of the war.
Meanwhile, in Europe, things essentialy devolve into three separate conflicts : France against Celtica (in Brittany), England against Celtica (in Ireland and Scotland), and the uprising in the various SSR (and the independent nations of Latvia, Lithuania and Estonia), backed by Germany, which keeps Soviet forces busy. Celtica, isolated by extensive Royal Navy blockades, soon begin to wither. In addition, in Asia, Japan attempts to invade Vietnam, but while they take Saigon, Hue and Hanoi, they are unable to make much progress beyond that, with the Viet forces holding the countryside with effective guerilla warfare.
By the end of 1930, France has retaken Brittany, and England is making good progress in Ireland, which had most of the resistance beaten out of it a decade earlier. Scotland, however, is managing to hold its own, as is Vietnam. The uprising is still ongoing in Europe, while the Japanesse have abandoned trying to wage war on the Vietnamesse, and are contenting themselves with holding the three cities, and maintaining naval patrol off the coast.
Late in november, Japan succesfully surprise the defenders of Vladivostok, and occupy the city.
On the last day of December, Britain formally recognize the independance of Scotland, which in turn proclaim its independance from Celtica, and signs peace with Britain. The treaty recognizes that Britain and Scotland shall now be two separate nations, with separate institutions, but in personal union and ruled by the same king or queen.
In the United States the Republican party has entered a spiral of self-destruction, its national credibility entirely lost. In Canada, the French have slowly begun arming themselves, and talks of independence in Québec are growing more and more prevalent.
Thus things stands on December 31st, 1930, as the world prepares to enter a new decade.
(Sorry, but let's be realistic here. It's been less than a decade since World War I ; Canada is still a british dominion populated by loyalists, Nothing has been done to make America less isolationist, and most of these "new nations" haven't even had the time to build a proper military, etc. Therefore, I tried to bring these factors into play while still making something interesting out of the previous posts.