I’ve retired my company in Battle Brothers after 365 days (because achievement). It was a Veteran/Veteran/Ironman game, though it wasn’t true Ironman as I would use the force-quit trick to replay some battles that went exceptionally poorly. Without that trick the run would have ended much, much sooner.
The run completed all three end-game crisis events, and at the time of retirement, a second greenskin invasion was happening. The witch’s hut major battle was beaten, but I could not complete the goblin city, black obelisk, or kraken battle. The reason I couldn’t beat those battles mostly came down to not having a massively min/maxed set of brothers, as I finished the campaign still using a mix of starter backgrounds along with some un-optimal higher-tier backgrounds. I’d say I had maybe three brothers who I would consider top-tier in terms of stats.
In terms of gear I had about 10 named items, along with full sets of high tier weapons and armor. The room for growth in this area was pretty slim, basically limited to more and higher-quality named items.
I’ve started a new campaign with the intent of seeing and beating all of the end-game content. Due to this, the run is not ironman, and I’m save scumming recruiting hard (buy everyone in a city, check stats, reload and only higher top-tier recruits, if any), as well as reloading any battles that go poorly. This of course leads to the game being overall easier, but that also means I’ll hit the power needed for those end-game battles faster. Once I see and beat those, I’ll retire the company and, most likely, start a true ironman run where I don’t use the force-quit trick, and just play until the company is wiped out.