Roman Herculian guard Adrian of Nicomedia, who had converted to Christianity after being impressed with the faith of Christians that he had been torturing, was martyred.

The Jovians and Herculians were the senior palatine imperial guard units under the rule of Roman Emperor Diocletian. They continued in existence thereafter as senior units in the field armies of the Western and Eastern Roman Empires.

Adrian of Nicomedia or Saint Adrian was a Herculian Guard of the Roman Emperor Galerius. After becoming a convert to Christianity with his wife Natalia (Ναταλία), Adrian was martyred at Nicomedia in Asia-Minor (Turkey). Adrian was the chief military saint of Northern Europe for many ages, second only to Saint George, and is much revered in Flanders, Germany and the north of France.

Christianity is an Abrahamic monotheistic religion, which states that Jesus is the Son of God and rose from the dead after his crucifixion, whose coming as the messiah (Christ) was prophesied in the Old Testament and chronicled in the New Testament. It is the world's largest and most widespread religion with over 2.3 billion followers, comprising around 28.8% of the world population. Its adherents, known as Christians, are estimated to make up a majority of the population in 157 countries and territories.

A martyr is someone who suffers persecution and death for advocating, renouncing, or refusing to renounce or advocate, a religious belief or other cause as demanded by an external party. In colloquial usage, the term can also refer to any person who suffers a significant consequence in protest or support of a cause.