Vespasian ( Titus Flavius Vespasianus , 17 November 9 AD â `` 23 June 79 ) , was Roman Emperor from 69 AD to 79 . Titus Flavius Vespasianus , commonly known as Vespasian ( 17 November 9 â `` 23 June 79 ) , was Roman Emperor from 69 AD to 79 AD .