Complex sentence: In theory, the Holy Roman Emperor was "primus inter pares" (first among equals) among the other Catholic monarchs; in practice, a Holy Roman Emperor was only as strong as his army and alliances made him.
Split into simpler sentences: In theory, the Holy Roman Emperor was "primus inter pares" (first among equals) among other Catholic monarchs. In practice, a Holy Roman Emperor was only as strong as his army and alliances made him.