Complex sentence: A six-star rank is a proposed or conjectural grade of military rank, above the five-star rank of a US general of the army, which in the United States has been used in reference to that country's formal title General of the Armies.
Split into simpler sentences: A six-star rank is a proposed or conjectural grade of military rank, above the five-star rank of a US general of the army. In the United States it has been used in reference to that country's formal title General of the Armies.