Masaccio joins the painters guild of Florence, signing as "Masus S. Johannis Simonis pictor populi S. Nicholae de Florentia."
The city of Aquila rebels and Muzio Sforza is sent to reconquer it. In an attempt to save one of his pages during the forging of the Pescara River, Sforza drowns and his body is swept away by the waters.
Jesus Honourable friend, I received your letter the fourteenth day of April and saw therefrom how dear and faithful a friend I have in you, and also that you are well. Also of your good mind toward me, which you have ever displayed; inasmuch that in case of need you would help me to polish one of these stories (reliefs) and would do it willingly: the which I know I can come only of love to me, for the which may God bless you. You must know, dear friend, that the stories are almost completed; one is in the hands of Giuliano di Ser Andrea, the other I have; and they will be finished at the time I promised Messer Bartolomeo; in sooth they would have been finished long since, but for the thanklessness of those, my past companions, from whom I received not one injury, but many. Thanks be to God, I am out of their hands, for which I ever praise God, considering in what freedom I now find myself. Being quite without company, I intend to remain thus, master in my own workshop and able to receive any friend with a good and cheerful countenance. I thank you for your perfect goodwill towards me. And I heartily beg you to commend me to Messer Bartolomeo. Also I beg you heartily to find, if you may, some means by which I may recover the drawings of the birds I lent to Ghoro (dir Ser Neroccio, a goldsmith of Siena). I know that it will be no pains to you to beg Master Domenico, the wood-carver, that he send them back to me, for I hear say that these and all other things that were in the hands of the said Ghoro are now with Master Domenico. Greet him from me, and likewise Master Francesco di Valdambrina: and if there be aught that I can do here, I am always at your pleasure. There is nothing other to say. May Christ keep you in peace. Writ on the sixteenth day of April 1425. By your Lorenzo di Bartolo, goldsmith of Florence, your dear friend
Masaccio is commissioned by Giuliano di Colino degli Scarsi da San Giusto, for the sum of 80 florins, to paint a major altarpiece, the Pisa Altarpiece, for his chapel in the church of Santa Maria del Carmine in Pisa.
Guillaume Dufay composes a motet on the Virgin Mary called "Flos Florum".