Final answer:
The emperor referred to is Gordian I, who ruled with his son Gordian II for one month before both their demise following a loss in battle against a governor loyal to Maximinus Thrax.
Step-by-step explanation:
The emperor you are describing is Gordian I, a short-lived emperor who ruled with his son Gordian II. Emperor Gordian I came to power around 238 CE during a period in Roman history known as the Crisis of the Third Century, characterized by civil strife, economic problems, and frequent changes in leadership.
Gordian I was co-emperor with his son for just one month before Gordian II was killed in the Battle of Carthage and Gordian I subsequently hung himself, they having lost the battle against the governor loyal to the emperor Maximinus Thrax.