In my experience winning the fighting with England in ironman is not the problem. The problem is getting the warscore above ~65%. Even getting from about 50 to 65% requires some luck (e.g., your allies/vassals have MA through Burgundy and siege Calais). I have not had too much trouble with third parties jumping in. Usually what I do is:
1. Divide stack into two, Send Jean Bureau to destroy the English stack in Normand, and a 2 reg stack to siege Caux. Send the other stack south to engage the other Limies. When all ENG troops are killed, siege all four for a year or two till they fall.
2. In the mean time, get a claim on Avignon. About the time you start to get stacks freed up from sieging, you'll have a claim on Avignon. Take it. This will usually involve war with either Savoy, Milan, Tuscany or Genoa. Best to get them to 100% first then take all their trade money and force them into some other zero AE peace deals.
3. Once you get Rome to 100% WS, start fabricating a claim on some Provence. Meantime, you'll want to start upping your relation with either Armagnac or Orleanais to annex them once you have peace.
4. If you are lucky and your allies siege Calais then you should get a WS up around 65%. This is enough to get them to release Guyenne or Normandy but not both. Do not recommend directly ceding anything as the AE will be very high. Instead either (a) accept release of only one (then start good relations with them to hopefully peacefully annex, or if necessary conquest; not getting a RM with Gascogne is a good idea if you are in a hurry as they are rich and snooty and might be standoffish about peaceful vassalization for quite a while).
5. If you are feeling particularly bold, and like you want to go for broke, here is the full measure: sometime after you've conquested Avignon (or Provence as you prefer), you'll want to start building cogs in Languedoc (you did move your fleet down 1st then on game start there right?). I generally like to build about 10 or 12 of them. As the HYW drags on, and if Calais is going back and forth between French-vassal and English hands, then the English AI will stop blockading Cote D'Argent quite so intensively. Even if they don't you can just sail around via ocean. Get an MA with Scotland and land them in the Highlands and hope that their stack of 18+ doesn't come and trounce your first wave. I find the more the better. 36 to 40 will generally get the job done.
6. Siege England to 100% WS, and Voila! you can get them to do something that is roughly like the historical outcome: they release Guyenne and Normandy, and you don't suffer much if any AE. There is generally enough WS left over for one or two other small concessions, maybe a treaty annulment or some cash.
Not true.
Once you win the sieges for the 4 English provinces in France, wait until you have enough warscore to force England to release Cornwall and return the most southern province back to Armagnac. Immediately ally and vassilize Cornwall. Now you have a base to load your troops into before the next war. Just before the truce expires, load all of your troops into Cornwall. (leave enough to siege the remaining 3 English provinces in France) Unless you've removed the guarantee and England is smashing Scotland, they always stockpile their entire army in London. Declare war on the first day of the month (making sure you're at full maintenance and morale) and march directly to their army, annihilate them, and England is your oyster. With this strat you can wipe them off the map in 4-5 wars. Tried and true method, I've done it probably 10 times without fail.
Also, if Portugal is an issue, either force them to break the alliance in the first war instead of releasing the province to Armagnac, or just raise a merc army to deal with them in the first war after vassilizing Cornwall. Another option, is upon starting the game, immediately (I mean, on the first day) royal marriage Spain before they rival you. In my most recent France game, I suddenly got a PU with them from nowhere a few years in. Portugal won't touch you with Spain backing you up. Having said that, in my experience, Portugal just wonders around southern France enjoying the scenery. They can't do enough damage to offset the pillaging you'll be doing in merry old England.
Or that would work too!
I found it is best to simply wipe the English of the continent, accept the southern cores and cash.
Immediately attack Burgundy, force them to release some dutch minors, if you can weaken them early you can pretty much do what you will after that.
I'm with you on the first part, but on the second part I differ. Rather than targeting Burgundy as my 2nd rival I tend to focus on Austria. A good trick I've found is to ally them, and then as I'm doing minor conquests (Brittany, Provence, etc.) I'll invariably get some insult CBs which they won't respond to. Use them to war them to 100% and force them to release Styria. In ironman, I've found that 99% of times Austria blobs after the Death of Burgundian king event and they become quite a handful. Best to carve them into a nice 1/3 before they ever get a chance.
ADDIT: and one more bit about invading England: as one guy said, you do not have to invade England to get them to let go of all four. This is part true. If you want to get them to release both countries (Guyenne and Normandy) you got two choices: (1) two wars, maybe three; (2) invade England. There is no other way to get to ~90 + WS that I know of. I suppose one other possibility that I have not focused on, so I cannot comment on the math of it; (3) cede two provinces and then do a 2nd war to get the other two.
In sum, without either two wars, or invading England, that is how it is gonna end in Ironman (which is why I made that "Historical HYW 1444 Start" mod: so it is possible for France to end it like it really did--> one war, no invasion of England, and England driven out of all four of those areas.
Comments on "how to" invade England. I like to use a force of about 12 cogs, the 3 early carracks you start with, and 3 or 4 barques (I think you also start with those. I use the barques to scout. In truth if that fleet gets attacked it is toast, but having a cheap ship one 'province' out in front to detect incoming enemies might save it.
Safest bet is to pay for the fleet basing if you can get if from Scotland. I've sailed around via ocean several times and a fleet can seemingly do that three about 3 maybe 4 round trips before you start to loves vessels. Three batches of 12 regiments is a nice force for taking one whatever England has there. They will likely have anywhere from 18 to 26 regiments. If you are a skilled EU combat player you can take even 26 with only 24 (two waves) but it doesn't leave much margin for error. That third wave makes it much less of a strain.
Get all three of them up there, staying north of England (as north as they can get!) and preferably in mountainous terrain. The English sometimes send up a stack of 18 if they think that what you sent is weak enough to kill it. This is why I recommend a fleet of 12 cogs. I've had a stack of 9 regiments get wiped out and had to wait another few months to rebuild them, plus more cogs.
Once you got your whole force there move largish stacks (12 to 18 forward first adjacent to one another. Likely the AI is hiding down by London. When you get a look what is ahead, move those large stacks ahead one more and then move your third stack up to the provinces they've left and slipt off one stack of 2 reg (2 inf, or 1 inf + 1 arty) for each province to be sieged. Extend yourself south carefully never splitting your lead stacks and keep the small stacks behind the lead stacks. One cyou get the northern provinces to fall, then continue to move south, always trying to presnt a consistently strong front and with the small 2 reg sieging stacks more protected or ideally "behind the lines" if you sent enough troops.
