The first years of Cosimo’s government were years of unrest and peril throughout Tuscany.  The adherents of the dead bastard Duke were neither few nor uninfluential.  Encouraged by the Clementine coterie in Rome, the members of which had from the first opposed Cosimo’s succession to the Headship of the Republic, they made the Florentine Court a hot-bed of intrigue and strife.

The party, not inconsiderable, which supported the claims of Giuliano, younger son of Pierfrancesco the Younger, and brother of Lorenzino, Alessandro’s murderer, gave much trouble.  Giuliano, who had been an associate of the Duke and an abettor of Lorenzino’s “devilries,” fled precipitately from Florence, and sought the protection of the Duke of Milan.  Lorenzino’s confession was written partly with a view of removing suspicion from his brother, and to leave unprejudiced the claims of his father’s family.  There were many other cliques and parties, great and small, each bent upon the other’s destruction in particular and upon the undoing of the Republic in general.

By far the most formidable opposition to Cosimo’s rule came from Venice, whence the Florentine exiles, under the command of Filippo negli Strozzi’s two sons, Piero and Roberto, who had married Lorenzino’s sisters, Laudomia and Maddalena, raised, with the assistance of the King of France, a strong force, and invaded Tuscany.

It needed not the persuasion of Madonna Maria to urge Cosimo to action, although her active representations to the Emperor—­which obtained the Imperial sanction and promise of co-operation—­were important factors in his resolution.  Cosimo gathered together what men he could rely upon in Florence, and when once his battle-banner was unfurled with the black pennon of his redoubtable father, numbers of old campaigners hastened to his support.

On 31st July, 1537, the opposing forces met in the valley of Montemurlo.  Cosimo displayed much of the daring and ability of his father, and victory was never in doubt.  The Strozzi and Baccio Valori were taken prisoners to Florence, bound upon broken-down farm-horses, and their forces were dispersed.  It was reported that in the heat of the battle Otto da Montanto, an Imperial officer, riding past Cosimo, lowered the point of his sword as he shouted, “Forward, Signore, to-day the fortunes of the Emperor and of Cosimo de’ Medici will prevail!”

Cosimo wore no velvet gloves in dealing with his enemies, secret and pronounced.  Arrest, confiscation, torture, banishment, and execution thinned once more the ranks of the noblest families of Tuscany.  Filippo negli Strozzi, who was regarded as the leader of the anti-Cosimo party, was taken prisoner and cast into the fortress of San Giovanni.  Apparently his aim was not a restoration of a Papal nominee to the Headship of the State, but his own advancement to that position.  He was put on the rack, and eventually done to death by Cosimo’s orders.

The years 1538, 1539 and 1540, are deeply dyed with the blood of victims.  Florentine vengeance again proved itself satisfied only with wholesale annihilation.  It has been computed that in the latter year alone, nearly five hundred men and women, chiefly of good family and high distinction, came by violent deaths.  Of these, one hundred and forty-six were decapitated by Cosimo’s express orders!