Short answers, pulled from the story.
Gordian II reigned for approximately 22 days in the spring of 238 AD, the shortest recorded reign of any Roman emperor. He ruled jointly with his father Gordian I before both died within the same brief period.
Gordian II was killed in the Battle of Carthage in April 238. He led a militia army of untrained soldiers against Capelianus, governor of Numidia, who invaded with the veteran III Augusta legion and other experienced units. According to the Historia Augusta, his body was never recovered.
Capelianus was the governor of Numidia and a loyal supporter of Emperor Maximinus Thrax. He also held a personal grudge against the Gordian family. When Gordian I and Gordian II declared against Maximinus in 238, Capelianus invaded Africa province and defeated Gordian II at the Battle of Carthage.
Gordian I killed himself upon hearing that his son Gordian II had been killed in battle outside Carthage. Both men died within the same 22-day co-reign in 238 AD.
238 AD is called the Year of the Six Emperors because six different men claimed or held the Roman imperial title that year. Gordian II and his father Gordian I were among them, reigning for only about 22 days before both died. Gordian II's nephew, Gordian III, was eventually recognized as emperor by the entire Roman world by the end of 238.
In the first volume of The History of the Decline and Fall of the Roman Empire, published between 1776 and 1789, Gibbon records that Gordian II had twenty-two acknowledged concubines and a library of sixty-two thousand volumes. Gibbon added in a footnote that Gordian had three or four children by each concubine.