Hungarian Democratic Republic
The shortest ever period was only 17 hours, a record held by Count János Hadik, from 30 October to 31 October 1918, who was asked to form a government by King Charles IV but the Aster Revolution broke out led by leftist liberal Count Mihály Károlyi, who founded the Hungarian Democratic Republic. By the end of the day, King Charles IV had accepted the coup and appointed Károlyi as Hungary's new Prime Minister. Hadik had no time to form a government, so many historians believe he was just a designated premier.