Unitas Fratrum (Unity of the Brethren) is the formal name of the group often referred to as the Moravian Brethren or Moravian Church. They were one of the very first Protestant groups in the world, originating from Jan Hus and the Bohemian Reformation of the 15th century in what is now the Czech Republic.
Fleeing religious persecution, they fled to Saxony in 1722, and some of them were given permission to settle on the land of a nobleman named Count Nikolaus von Zinzendorf, a Lutheran Pietist who had a large estate outside of Berthelsdorf.
The Moravian Protestants who settled there, together with Zinzendorf, established a church and named their settlement Herrnhut (The Lord’s Watch). One characteristic of their new community was continuous prayer, done in shifts by different people. This continuous prayer at Herrnhut went on uninterrupted for 100 years.
What is particularly significant about the Moravian church at Herrnhut is that they were a missionary church. They were the first large-scale Protestant missionary group, and they were the pioneers of the modern missionary movement.
During the eighteenth century alone, the Moravians established mission outposts in the Virgin Islands (1732), Greenland (1733), North America (1734), Lapland and South America (1735), South Africa (1736), and Labrador (1771).
Their all-consuming purpose was to spread the gospel to the ends of the earth, a passion that was evident in their proportion of missionaries to laypeople, by some estimates a ratio of 1:60.
Some of the very first Moravian missionaries went to the Caribbean island of St Thomas. They went there in order to minister to the slaves on the island, even selling themselves as slaves in order to get access.
The Moravians had learned that the secret of loving the souls of men was found in loving the Savior of men. On October 8, 1732, a Dutch ship left the Copenhagen harbor bound for the Danish West Indies. On board were the two first Moravian missionaries; John Leonard Dober, a potter, and David Nitschman, a carpenter. Both were skilled speakers and ready to sell themselves into slavery to reach the slaves of the West Indies. As the ship slipped away, they lifted up a cry that would one day become the rallying call for all Moravian missionaries, “May the Lamb that was slain receive the reward of His suffering.” The Moravian’s passion for souls was surpassed only by their passion for the Lamb of God, Jesus Christ. (Source)
I don’t know about you, but it challenges me to see that these people were willing to sell themselves into slavery in order to minister to people they had never met before. That is radical love and radical self-sacrifice. It expresses true belief in the importance and urgency of people coming to know the good news of who Jesus is and what He has done.
This attitude is absolutely counter-cultural, not only in our day, with our extreme focus on self, but also in every generation, since humans are naturally inclined to self-centeredness. This radically different approach to life and others comes from having a Savior and a God who gave up everything to save enemies and rebels, out of love for us.
For while we were still weak, at the right time Christ died for the ungodly. For one will scarcely die for a righteous person—though perhaps for a good person one would dare even to die— but God shows his love for us in that while we were still sinners, Christ died for us.
For if while we were enemies we were reconciled to God by the death of his Son, much more, now that we are reconciled, shall we be saved by his life. (Romans 5:6-8,10)
To read more about the Moravians and their hearts for prayer and missions, you can check out the entire article this excerpt comes from.
I also recommend this book for those interested in the history of Christian missions: From Jerusalem to Irian Jaya: A Biographical History of Christian Missions.