The richer a nation is, the more practical it is to make it a protectorate. They also have friendlier relations with their protector faction thanks to their status as an ally. Protectorates also automatically grant indefinite military access to their protector faction. Protectorates cede some of their income to their protector nations, in exchange for a pledge from the protector faction to ally itself with it and declare war on enemies invading the protectorate and vice versa. All protectorates are counted as allies, and function in a largely similar way with a few key differences.
Any faction, regardless of if they are major or minor, may become protectorates if these conditions are met. Factions may only request other factions to be protectorates if the requested faction has only one region left. No faction can be the protectorate of more than one faction at a time. However, should the nations be at war, then one nation becoming another's protectorate can be part of the terms of a negotiated peace. Under normal circumstances, a faction cannot ask another faction which is already a protectorate to become a protectorate.
Players may choose to request other nations to become their protectorate in the diplomacy screen. A protectorate is a faction under the protection of another faction. Protectorates are a gameplay mechanic in the Total War series.
