What are the views of St. John Cassian on participating in military service?

In The Institutes , he discusses the renunciation of the world (in daily life and the virtues appropriate to it) and writes for the benefit of those who abandon this world.⁹⁸⁶ He says that the monk begins with true humility and complete obedience as the basis on which he ascends to the heights of other virtues. He presents a few examples of the behavior of some of the elders who were eminent in this virtue. His first example is Abba John , who lived near Lycopolis (Asiut) in the region of Thebes, and who attained to the gift of prophecy because of his astonishing obedience. He even became famous among the kings of this world, such that “the Emperor Theodosius did not venture to declare war against the most powerful tyrants before he was encouraged by his utterances and replies: trusting in which as if they had been brought to him from heaven he gained victories over his foes in battles which seemed hopeless.”⁹⁸⁷

In the Litany of the King (or Ruler) in the Liturgy of St. Cyril the Great we pray, “May all the barbarians, the nations that desire war against all our prosperity be subdued unto him.”

984 St. Augustine of Hippo, The Works of St. Augustine: A Translation for the 21st Century: Part III— Sermons; Volume VIII: Sermons 273-305A , trans., Edmund Hill, ed., John E. Rotell (New City Press, 1993) 302.15: p. 307.

985 St. Augustine of Hippo, Letters 47 (FOTC 12:230).

986 St. John Cassian, Institutes 4.23 (NPNF II/11:226).

987 St. John Cassian, Institutes 4.23 (NPNF II/11:226).