the second Duke of Florence from 1537 until 1569, when he became the first Grand Duke of Tuscany. Cosimo was an authoritarian ruler and secured his position by employing a guard of Swiss mercenaries. In 1548 he managed to have his relative Lorenzino, the last Medici claimant to Florence, assassinated in Venice. Cosimo also was an active builder of military structures, in an attempt to save his state from the frequent passage of foreign armies.
