Vartan Mamikonian -Armenian: Վարդան Մամիկոնյան -393 AD - 451 AD-, is also known as Saint Vartan – An Armenian military leader, a martyr and a saint of the Armenian Church. He is considered one of the greatest military and spiritual leaders of Christian Armenia in the 5th century.

Vartan Mamikonian, a member of one of the most powerful aristocratic families in Armenia, Mamikonian dynasty, born to Hamazasp Mamikonian and Sahakanoush Mamikonian, daughter of Saint Sahak the Great; and a descendant of the Arsacid Kings and Saint Gregory the Illuminator.

His father, Hamazasp, was the sparapet, or commander-in-chief, of Armenia at that time. Saint Vartan was educated by his grandfather, Saint Sahak and many would consider that a wonderful education for the time. Rather than entering the priesthood, as others of his family had done, he courageously chose the life of the military and became a soldier, eventually becoming Commander-in-Chief of the Armenian army.

Political matters in Armenia during the mid-5th century were tumultuous at best, and this made it increasingly difficult for Christian-Armenians to practice their faith. The Persians, who occupied various Armenian regions, had initially allowed Armenians to retain their own laws and practices. However, because of the Armenians growing zeal for their religion, and the loss of Persian influence (time and distance eroded their control) the then reigning Persian ruler, King Yazdigerd II, a cruel and evil man, as well as a ruthless ruler, demanded that the Armenians abandon their religion, and submit to the precepts of the pagan Persian religion –Zoroastrianism, to worship fire. King Yazdigerd II was fanatically opposed to Christianity, and he was particularly cruel to the Armenian people. In addition to his attempt to compel them to abandon the faith, he also imposed unfair taxes on them.

This decree alone was reason enough for a fierce revolt in Armenia, where the people gathered around their national leader, Vartan Mamikonian. The Armenian priests, led by the Armenian Catholicos, gathered in 450 in Ashtishat and wrote a letter declaring their firm loyalty to Christianity.

Even in this national revolt, which once again united Armenia, there were a number of noblemen who betrayed their country and their people. These noblemen, who either feared the Sassanid’s' revenge or were acting in their own interests, joined the Persian side in order to win their favor.

The Battle of Avarayr or Avarayri chakatamart is one of the most significant battles of the Armenia’s history. Taking place on May 26, 451 AD, on the field of the Avarayr plain in Vaspurakan, and is remembered as the greatest spiritual and moral victory gained for all Armenians. The battle was fierce and bloody, with many casualties on both sides. The spirituality of the 66,000-strong Armenian army had them take Holy Communion before the battle, the ritual even more solidly cementing their determination.

The Persian force is said to have been three times larger, with ferocious war elephants, and their famous (or infamous) Savārān, or New Immortal, cavalry. 
Although St. Vartan and many of his comrades, were in fact defeated that day, and killed in the battle, their fierce fight to defend their faith, and to be simply BE Christians, was not in vain.

Eventually the Persians stopped their efforts to convert Armenia to Zoroastrianism.

Armenian resistance to their occupation continued in the decades following the battle, led by Vartan's successor and nephew, Vahan Mamikonian. In 484 AD, Shah Peroz I signed the Navarsak Treaty, which guaranteed religious freedom to the Christian Armenians – (who were, however, no longer in communion with Rome or Constantinople) , and granted a general amnesty with permission to construct new Christian churches to the population.

For these reasons Armenians see the Battle of Avarayr as a moral victory; and May 26 is considered to be a holy day by Armenians, one of the most important national and religious days in Armenia.