In their title, the Commentaries of Pope Pius II recall the works of Julius Caesar by the same name. The connections between these ancient and humanist histories, however, run much deeper. This article explores this relationship in detail and in the broader historical and historiographical contexts of fifteenth-century Italy. It argues that in both Caesar's histories and in his career more generally, Pius found much that resonated with his own experiences, challenges, and goals. More importantly, he found in these ancient Commentaries valuable apologetic strategies for constructing his own textual self-portrait as both pope and prince. In choosing Caesar's histories as his models, Pius was following a recent historiographical precedent. Several Italian Renaissance humanists had also turned to Caesar's works as guides for writing histories about leaders of contemporary temporal politics. This article argues that by adopting the same models when shaping his own image, Pius was effectively politicizing his self-portrait in his Commentaries.