Land Forces not moving

Country Asria onn WG

I am in a War with a c3 and have for land units not of which have moved in over a (game) year. I checked thy have supplies and my supply units are idle So I don't know what else it could be

Forces are not moving due to garrisons preventing further occupation. You must destroy targets with garrisons in order to progress in occupying the country.

That makes sense thank you