Here is the map of who is in the war:
The Roman Empire
Allies of the Roman Empire
Co-belligerents with the Roman Empire
Enemies of the Roman Empire
Puppet states of the enemies of the Roman Empire
Roman territories occupied by the enemies of the Roman Empire
Allied territories occupied by the enemies of the Roman Empire
Enemy territories occupied by the Roman Empire
Enemy territories occupied by allies of the Roman Empire
Neutral countries
Unclaimed territories
An excerpt of from a speech by the Emperor:
The Roman Empire sends a general request to the neutral nations of the world to enter the war on its side. We cannot allow the aggressors to take apart the Empire, for who knows what they will do next? The will plunge the world in eternal warfare with their greed and impunity, destroying the remaining neutral nations - And destroying the freedom and liberty of our peoples. Attempting to take apart a nation for no reason is greedy, aggressive, and endangers everyone involved.
On another note, here is a series of messages between the Roman and Rio Grande governments before the Rio Grande government invaded the Roman Empire: this shows how treacherous the aggressors are, and how their governments have not got the slightest sense of decency:
Spoiler :

The Roman Empire
Allies of the Roman Empire
Co-belligerents with the Roman Empire
Enemies of the Roman Empire
Puppet states of the enemies of the Roman Empire
Roman territories occupied by the enemies of the Roman Empire
Allied territories occupied by the enemies of the Roman Empire
Enemy territories occupied by the Roman Empire
Enemy territories occupied by allies of the Roman Empire
Neutral countries
Unclaimed territories
An excerpt of from a speech by the Emperor:
The military events which have happened during the War have not come to me with any sense of surprise. Indeed, I indicated as clearly as I could to my advisers and generals that the worst possibilities were open; and I made it perfectly clear then that whatever happened during the invasion would make no difference to the resolve of Rome and the Roman Empire to fight on, if necessary for years, if necessary alone.
The Roman Empire sends a general request to the neutral nations of the world to enter the war on its side. We cannot allow the aggressors to take apart the Empire, for who knows what they will do next? The will plunge the world in eternal warfare with their greed and impunity, destroying the remaining neutral nations - And destroying the freedom and liberty of our peoples. Attempting to take apart a nation for no reason is greedy, aggressive, and endangers everyone involved.
On another note, here is a series of messages between the Roman and Rio Grande governments before the Rio Grande government invaded the Roman Empire: this shows how treacherous the aggressors are, and how their governments have not got the slightest sense of decency:
