Titian had in mid-1548 accepted the invitation…
September 1548 CE
Titian had in mid-1548 accepted the invitation of Holy Roman Emperor Charles V to go to the imperial court of Augsburg, where he paints, among many other portraits of illustrious personages assembled for the Diet of Augsburg, Emperor Charles V on Horseback, one of his most distinguished works (and the prototype for equestrian portraits by later artists).
Also Emperor Charles V on Horseback and Charles V at Mühlberg, an oil-on-canvas painting created between April and September 1548, the work is a tribute to the emperor following Charles' victory in the April 1547 Battle of Mühlberg.
Titian knows Charles personally, and has painted a number of portraits of him by this time.
Mary of Austria, Queen of Hungary, had commissioned the portrait.
(It enters the Museo del Prado's collection in 1827.)