His father, Cosimo II, died on 28 February 1621; he was succeeded by Ferdinando de' Medici, the elder son.

He took part in the famous battle of Lützen,[3] in November 1632, where he met Sienese General Ottavio Piccolomini.

[citation needed] Mattias adored the arts, patronising Justus Sustermans, Volterrano and many other eminent artists.

While in Germany, he acquired scientific instruments, such as dials, astrolabes and compasses; all of which he later deposited in the Uffizi.

[citation needed] In later life, suffering from gout, he pondered re-assuming ecclesiastical garb; however, he fell ill and died in Siena on 11 October 1667 at 54 years of age.