The 59th mitzvah is that we are commanded to sound the trumpets in the Holy Temple when offering any of the periodic1 sacrifices.

The source of this commandment is G‑d's statement,2 "And on the day of your rejoicing, on your festivals and on your Rosh Chodesh days, you shall sound the trumpets over your burnt-offerings."

Our Sages have explicitly stated3 that [on a fast day, the sounds of the trumpet last longer than the sounds of the shofar4 because] "the main mitzvah of this day is that of the trumpets."5

The details of this mitzvah are explained in the Sifri,6 in Rosh Hashanah,7 and in Taanis.8

Since we are [also] commanded to sound the trumpets when we cry out to G‑d (exalted be He) during a time of trouble and distress, the verse9 says, "When you go to war against an enemy who attacks you in your land, [you shall sound the trumpets]."