Unified field theory classical field theory and, two years later, that of Theodor Kaluza, who extended General Relativity to five dimensions. Continuing in this latter direction, Oscar Klein proposed in 1926 that the fourth spatial dimension be curled up into a small, unobserved circle. In Kaluza–Klein theory, the gravitational curvature of the extra spatial direction behaves as an additional force similar to electromagnetism. These and other models of electromagnetism and gravity were pursued by Albert Einstein in his attempts at a classical unified field theory. By 1930 Einstein had already considered the Einstein–Maxwell–Dirac System [Dongen]. This system is (heuristically) the super-classical [Varadarajan] limit
Unified combatant command forces in an efficient "unified combatant command" force. Furthermore, the Secretaries of the Military Departments (i.e. Secretary of the Army, Secretary of the Navy, and the Secretary of the Air Force) are legally responsible to "organize, train and equip" combatant forces and, as directed by the Secretary of Defense, assign their forces for use by the combatant commands. The Secretaries of the Military Departments also do not exercise any operational control over their forces. Each combatant command can be led by a generalor flag officer from any of the military services. Unified combatant command A unified combatant command (UCC) is