Automatic Tech-ing

When you make technological advances once they come into being do all your units (that can) automatically benefit or do they need to be retrained like in previous titles?

I only ask because my bayonets have been teched and I had the 'fix bayonet' option. Once I teched again this disappeared. I presume this is because you can take the bayonets off now, whereas before the 'fix bayonet' option also meant you couldn't fire anymore.

Thanks

Yeah, once you get ring bayonets, they are automatically on the muskets.

If in doubt, check it out. (in game)

Retraining is never needed, all bonuses are immediately applied everywhere.