INTERREGNUM (Lat. inter, between, and regnum, reign), strictly a period during which the normal constituted authority is in abeyance, and government is carried on by a temporary authority specially appointed. Though originally and specifically confined to the Sphere of sovereign authority, the term is commonly used by analogy in other connexions for any suspension of authority, during which affairs are carried on by specially appointed persons. The term originated in Rome during the regal period when an interrex was appointed (traditionally by the senate) to carry on the government between the death of one king and the election of his successor (see ROME: History, ad init.). It was subsequently used in Republican times of an officer appointed to hold the comitia for the election of the consuls when for some reason the retiring consuls had not done so. In the regal period when the senate, instead of appointing a king, decided to appoint interreges, it divided itself into ten decuries from each of which one senator was selected. Each of these ten acted as king for five days, and if, at the end of fifty days, no king had been elected, the rotation was renewed. It was their duty to nominate a king, whose appointment was then ratified or refused by the curiae. Under the Republic similarly interreges acted for five days each. When the first consuls were elected (according to Dionysius iv. 84 and Livy i. 60), Spurius Lucretius held the comitia as interrex, and from that time down to the Second Punic War such officers were from time to time appointed. Thenceforward there is no record of the office till 82 B.C., when the senate appointed an interrex to hold the comitia, which made Sulla dictator (Appian, Bell. civ. i. 98). In 55, 53 and 52 interreges are again found, the last-mentioned being on the occasion when Pompey was elected sole consul.
The most noteworthy use of the term " Interregnum " in post-classical times is that of the Great Interregnum in German history between the death of Conrad IV. (1254) and the election of Rudolf of Habsburg (1273). See GERMANY: History.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)