I clearly do not fully understand the logistics of naval transportation in Europa Universalis IV. I managed to send 5000 cavalry to their death in Tangiers when I went to help Portugal in their war against Morocco because I managed to leave behind 15,000 foot soldiers on my own shores. In Civ V you just click the military unit on land and have it move to a water tile, it just disembarks, with EU I actually have to have enough ships to carry 20 regiments and I didn't.
How do you track your aggressive expansion attitude modifier that other nations have towards you?
I'm playing as Castille and just took over Grenada in the Reconquista. I had casus belli and didn't take too much of an aggressive expansion modifier. I have military alliances and royal marriages with Portugal and Navarre. I've used a diplomat to improve relations with Navarre to the point where I could make them a vassal (something I saw quill18 do, I don't know why I want them as a vassal, I just did it). I have been trying to achieve a diplomatic alliance with Aragon and have dramatically improved their opinion of Castille but they haven't done the same so things like a military alliance or royal marriage are completely off the table. They've named me a rival and have done nothing to improve relations.
The thing is, Aragon are in a war with Genoa--which apparently is a thing and I never want to ally myself to Genoa--and most of Aragon's navy and a good portion of their army are off engaged in that. Because I've been trying to achieve a peaceful relation with them, I haven't been fabricating claims on their provinces and have no casus belli buuuuuuuut I could siege and take all of their provinces on the Iberian peninsula right now. I just don't want the rest of the surrounding kingdoms to make an alliance against me because I'm a war mongering douchebag.
I think I'll simply stop my game and watch
quill13's playthrough of Castille some more. I'm actually a bit ahead since I managed to not get into a war with Aragon, made Navarre a vasal and have full conquered Grenada.