I just beat the Barbarossa campaign, which means I am done with my quest to beat all the AOE2 campaigns for the first time in my life. That being said, I will not be attempting the Battles of the Conquerors. While those standalone missions are certainly of historical interest, I was primarily concerned with completing the multi-part campaigns. After all, it was my failure to beat those campaigns that haunted me for years. I should note that when I set out to do this a month or so ago, I planned to start by replaying the last two William Wallace missions. Unfortunately, I had to scrap those plans when I found out I couldn't change the difficulty to Hard. Also, do I regret not beating these campaigns on AOK's Hardest difficulty? Not really. Hard was enough of a pain, and I'm shocked that I'm not writing this from an insane asylum.
Now, onto my comments on the Barbarossa campaign. Unsurprisingly, this was no walk in the park. Only the opening mission was fairly straightforward, and that was a 1-on-6 scenario! Every other mission had at least one gimmick that made it tricky or downright hard. While the 5th and 6th missions required a lot of patience, persistence, and intestinal fortitude to get through, I'd actually say the 4th one was the most challenging. Dealing with constant land-based attacks while also fending off an endless stream of Cannon Galleons was a hassle I'm glad to put behind me. All in all, the previous campaigns prepared me well for these and other miseries.
Oh, and one final thing. Whenever I beat a mission, I'd read up on what the AOE2 fandom wiki and StrategyWiki had to say about it. I don't know who wrote the latter's walkthroughs, but he kind of annoyed me. First of all, his guides were long - much, much longer than these write-ups I've been posting. It seemed like he was addressing newer players, which would be alright if he were more to the point. Secondly, he took just about every opportunity to try and discourage cheesing the missions. I found this utterly ridiculous, especially since he equated having prior knowledge of events with cheating. Whether he was being serious or not, I'll never know. All I can say is, this game is hard enough as it is even with some prior knowledge. I highly doubt your average player would successfully complete quite a few of those missions on their first blind playthough. And lastly, his AOK guides don't account for the AI having researched Heresy (the AOC-introduced tech that kills converted units rather than switching their color). It really threw me for a loop when he'd say something like, "Your forces will be vastly outnumbered, but don't worry - you'll convert dozens of enemies to your side!" Since the majority of players are likely playing a version with the AOC expansion included, I would've thought the StrategyWiki walkthroughs would have reflected this. I didn't think the website was that old, but whatever.