As for the ships, here is the first.
Historical Background
The Viridisian Navy realized the need to update it's surface force in the 1970s, which was composed of two (2) ex-Royal Navy River class frigates, four (4) ex-Royal Navy Algerine class minesweepers converted into corvettes, as well as smaller assets suited for coastal patrol and interdiction. This was because of the expansion of Soviet forces in the Mediterranean, which in the Navy's current state, can't adequately combat these new threats.
The Italians offered to sell three corvettes to Viridisia, with an option of the third unit to be built locally, this was already in advanced negotiations when the newly elected Curio government in 1978 cancelled the talks, opting the ships to be locally designed and built. This was part of his government's efforts to revitalize the country's local enterprises by promoting local industries. The initial corvette was launched in 1984, and the third and final unit entered service in 1987.
The Urben class of corvettes provided the necessary upgrade in Viridisian naval forces. They would be the core of the Navy's surface force till now, and would be replaced by a new class of corvettes soon.