Here is Father Kunst’s Commentary:
This was actually written while Pius II was a cardinal. And so his first name was ‘Enea’, so he signed with the initial ‘E’. He was the Cardinal of Siena at the time. This is dated 1457. Actually what he was doing was writing a letter of recommendation for a man to be the police chief of Siena.
Again, this was prior to his pontificate, but the mere fact that it’s actually signed by him, as opposed to some of the older papal bulls that are not signed, makes this significant, because it is the oldest one I have with a signature of a (future) pope.
So he’s writing to the secular head of Siena with his recommendation for a chief of police.
The letter is dated October 6th, 1457. It is simply signed, E, as the Cardinal of Siena. It is a letter to the City Council of Siena, recommending a particular man to be the Chief of Police (or Commander of the City Forces). He commends him as a reliable person currently running the police force in Ancona. It is in very good condition and dated a year prior to his pontificate.
Pope Pius II was Cardinal Eaneas Sylvius Piccolomini.