popes sent them into the heart of Protestantism to "win back lost souls".

The Jesuits

The Jesuits played a very important role in the Counter-Reformation. 

The founder of the Jesuits, Ignatius Loyola, must be seen as a key player during it. Loyola was the son of a Basque nobleman and was born in 1491. He became a soldier who was fond of women and gambling - and he had a  typical upbringing for a richman’s son with enjoyment taking a precedence within his life with no obvious professional calling. 

In 1521 he fought in the army of Charles V. While defending Pampuna he was hit by a cannonball and badly damaged his left leg. 

While recovering from this injury, he suffered a crisis believing that his life seemed purposeless. 

He took to reading about the life of Christ and the Saints. He saw a vision of the Virgin Mary and the baby Jesus and he went to the shrine of Our Lady at Montserrat in Aragon and became a hermit living in a cave  

The Jesuits were held in such high regard that popes sent them into the heart of Protestantism to "win back lost souls". They went without dissent despite the obvious dangers to their own well—being and liberty. Their commitment, as Loyola had demanded, was fierce possibly even fanatical.