The Frisian army in Oldenburg was quickly moved back to Friesen, where it was reinforced with 6000 men. The Frisian navy (20 galleys) was already in place outside the capital, protecting it and Holland. The only place Burgundy and England could directly access Frisian lands was in Artois. My plan was to leave Artois alone, and instead focus on capturing Burgundian provinces. When 20 days of the war had passed, great news arrived to the Frisian court:
Notice that the Frisian alliance is still in a war against Holstein
Dauphiné on our side will surely be helpful. Burgundy immediately stood off and focused on their southern borders. England, meanwhile, seemed unafected by the DoW and besieged Artois with 46000 men. The members of the Frisian alliance were of course motivated by the good news, and thus Flandern was besieged by a large combined army from Geldre, Bremen, Oldenburg and of course Friesland. Unfortunately, Geldre started the siege, so the Frisian army tried to take Brabant instead.
A year passed, and things looked bleak for Friesland. England took Artois, and moved their army through Brabant where they easily beat the Frisians. Then England moved into Holland with 5000 men. Even if the Frisian army was badly beaten at Brabant, I followed the English and managed to send them out in the ocean outside Holland on the second attempt. Meanwhile, Geldre was doing well and captured Flandern. England bought them out of the war for 310 ducats in 1437.
Even if I had lost the support of the armies from Geldre, I made a new attempt at taking Flandern. After being routed by Burgundy a couple of times, I finally managed to capture it in 1439. The good news were countered by the English annexation of Bremen and capture of Oldenburg. Since Oldenburg was my vassal, the English wasn't able to annex them right off the bat, fortunately.
Even if Burgundy and England had the upper hand, Burgundy surprisingly sent me this offer:
The war against England continues though
I'll take it! The Frisian army moved into Artois to liberate it.
England must have been furious by the Burgundian capitulation, as they moved thousands of men into Friesen. When the capital was captured, they had no way of reaching Holland, because the straits were blocked. The Frisian navy had been largely uncontested during the war, but England was now ready to strike. With more than twice the size of the Frisian navy, it was an easy victory for the English fleet. Holland was soon besieged.
With no support from my navy, it would have been no problem for the English to take Flandern too. After a long time of thinking, I decided to cave in to Englands demand for Artois and 2 ducats. Even if I really wanted to keep Artois, "trading" it for Flandern was a good bargain. The war against Holstein ended with a white peace soon afterwards, the same with the war between England and Dauphiné (200 ducats to the French).
England wasn't finished with warmongering though, as they declared war on Aragon. While they were busy in Spain, all of their northern French provinces revolted. Interesting. Meanwhile, in Friesland, things were looking good. A loan from the war was repaid at first opportunity, much due to the riches from Flandern. Flandern did prove valuable in diplomatic aspects too, as Geldre became vassals of Friesland in 1451. Excellent! I thought it was a longshot due to Geldre's large armies, but they accepted nevertheless.
England didn't manage to liberate their rebel-controlled provinces, and thus Hainault declared independence in 1454. Also, Calais revolted to Friesland, which is both good and bad. Good, because it is fairly rich. Bad, because England now got a CB on me. The rest of the northern French provinces revolted to Burgundy. In addition to that, Bremen revolted too. England: overextending is never smart. To rub it in, Wales revolted too. Both Hainault and Wales didn't live for long though, as the former was annexed by Burgundy and the latter by England.
Bremen was annexed by Holstein, which in turn was diploannexed by Denmark. It's an unstable region Friesland is living in... Also, I don't like the size of Burgundy now.
Army 15000 cavalry + some infantry, Navy: 30 galleys. Gotta love Flandern.
Allies: Geldre, Oldenburg, Cologne and Lorraine
Vassals: Geldre and Oldenburg
Techs: On par with rest of Europe. Got Infra 3 in 1457!