The history of the Church tells us Yes. Two examples - one a Christian ruler, and the other a Christian soldier (emphasis added below).
St Alexander Nevsky (1263)
"Nevsky" means "of the Neva (River)." This holy prince guided Russia through one of the most fragile and difficult periods of its history. Most of the nation was crushed beneath the 200-year domination of the Tatars, who burned Kiev and established their central territory (known as the Golden Horde) there. At the same time, Teutonic and Swedish Christian invaders sought to conquer from the West, and Pope Innocent IV of Rome was seeking, by conversion or conquest, to pervert the Orthodox faith of the Russian people. At the same time, constant warfare among petty Russian lords made unified work on behalf of the people almost impossible. In this harsh climate, Prince Alexander of Novgorod shone as that rare thing: a truly Christian ruler. In time of famine he opened his treasury to all who were in need. Several times he traveled to the Golden Horde, and even to Mongolia , to plead on behalf of his people for relief from Tatar taxation and oppression.
Soon after he became prince of
When he was summoned for the first time to pay homage to the Khan, he went as if to his own death, for the Khan required his subjects to submit to pagan rites or die, and the prince knew that he would never betray the Faith of Christ. Before the Khan, he said "My liege, I do homage in that God has granted you sovereignty, but I am unable to worship idols because I am a Christian and adore the one and only God in three Persons, the Maker of heaven and earth." The Khan, knowing of his valor and impressed by his integrity, received him as an honored guest.
In another visit to the Golden Horde, the prince averted a Tatar invasion in retribution for an uprising by another prince, dug deeply into his treasury to ransom prisoners, and was given rule over all of Russia .
Threats from the West continued. Prince Alexander firmly opposed the missionaries sent into his realms by Pope Innocent IV of
In 1260, the holy Prince made a final journey to appeal to the Tatars, who had increased the tribute levied on the Russian people, and were carrying those unable to pay into slavery. Having obtained a reduction of tribute and relief for his people, he headed home but, on the journey home, exhausted and ill from his labors, he gave up his soul to God in 1263, having served his people without rest until the end. On his deathbed he received the monastic Great Schema and the new name Alexis.
"Many miracles and apparitions have taken place at his tomb, especially on the eves of the great Russian victories over the Tatars in 1380, 1552 and 1572. The sanctity of the holy Prince was formally recognized by the Church in 1380, when his incorrupt relics were uncovered. In the eighteenth century, Peter the Great proclaimed Saint Alexander Nevsky Protector of the Russian people." (Synaxarion)
Source: Entry for 23 November at http://www.abbamoses.com/months/november.html (accessed 29 Nov. 2013)
Holy Martyr Mercurius of Smolensk (1238)
He was a soldier from Byzantium , one of the defenders of Smolensk when it was besieged by the Tatars in 1238. One day the Mother of God appeared to Mercurius and told him that the Tatars were preparing a surprise attack — and, further, that he must take up arms and attack the enemy singlehandedly. Placing all his trust in God, the lone soldier threw himself against the Tatar host crying 'Most Holy Mother of God, help me!' He was quickly surrounded and cut down, and it appeared that his action had been as foolhardy as it had seemed, when a woman at the head of a glorious host, all of them surrounded by light, appeared and threw back the Tatar army. The next morning the people of Smolensk found the ground covered with the bodies of their enemies. They buried Mercurius in the Cathedral, where he has been venerated as a Martyr ever since.
Source: Entry for 24 November at http://www.abbamoses.com/months/november.html (accessed 29 Nov. 2013)
For a more detailed account, the reader is invited to follow this path:
Icon courtesy of the OCA
To underscore the point made in Acts 10 with the conversion of the centurion Cornelius, and above with St Mercurius of Smolensk , that a soldier fighting in defense of his homeland is not a sin before God (as opposed to a war of aggression motivated by greed or other vices), in the life of another Martyr Mercurius (this one from the 3rd century A. D.), we find this notable passage:
‘During a campaign, an Angel appeared to him, gave him a sword and told him to go into battle trusting in Christ's help.’
Source: Entry for 25 November at http://www.abbamoses.com/months/november.html (accessed 29 Nov. 2013)
This is something Southerners, being a family, understand well, and it was manifested quite distinctly during the War of Northern Aggression. Yet with notions of pacifism in the air, it is good for us withal to place the clear teaching of the Church before our eyes.
But as to the former point, let no one despair: Even in the darkest of times, the Lord is able to deliver any people from evil if there is present an humble and righteous man or woman willing to serve Him (other examples: Noah, Moses, the Judges, David, St Ælfred, etc.). Only let those peoples and nations make themselves worthy of deliverance from outer bondage by conquering their inner passions.