Are these units really useless?

[Eagle Pursuit]

I really like Privateers. They are invisible and coastal raiding is a fun reprisal when you can't be bothered to go conquer your intercontinental rivals.

Now, they don't exactly take the place of Frigates. But they are way more fun.

 

[teks]

As I recall, the combat boost to a unit when a support is present is a level 2 promotion within the anti-calvary class. (Spears & Pikes)

It doubles the bonus that already exists. From +4 to +8, which is weak. But. Support units give all units +4 if they share a tile. Same bonus as a forest or hill if I remember right, and that's not counting their actual function.