Glorious Showoff

Hello, my name is Glorious Showoff and I'm just a nomad who is just getting into this franchise, it seems awesome! I came joining onto here with the intent of asking for support when it comes to Fire Emblem Warriors due to me being stuck on one of the History Mode chapters that I just posted in the Fire Emblem Warriors section, I hope to be active on here when I can. If you could help me with my current struggle regarding Fire Emblem Warriors, that would highly be appreciated, thanks!

Hi there. I'm currently on doing the History Mode of this game with the map being the Path is Yours. I am on the Xander battle but am stuck. I have seized every single fort and outpost, and defeated practically every one of Nohrian's important forces besides Xander himself, this is because the enemy base gate is seizing to open. What do I need to do in particular to have that gate open? No matter how much enemies I'm fighting with all forts seized, it's not opening. That being said I failed the mission of stopping the summoner from calling scouting troops so maybe that might have to do with it so there's that to throw into the wind as well, if there's any solutions please let me know as soon as you can.