Answer:
The Counter-Reformation was an organization within the Catholic Church dedicated to fighting the consequences of the Protestant Reformation and undoing them by reforming Church abuses and eliminating heresies, etc. It could be argued that it began formally in 1545 with the Council of Trent, which was opened by Pope Paul III specifically to strengthen the Church in the face of the revolutionary developments in the Protestant countries of northern Europe. This happened more than 20 years after the beginning of the Protestant Reformation, and it was so given that the Catholics themselves had various political conflicts among their main leaders of each nation.
The Counter-Reformation was at its peak in the second half of the 16th century but continued until the middle of the succeeding century. The establishment of the Society of Jesus (the Jesuits) and its development into a missionary body sending priests to all parts of the world, from Peru to China and Japan, seek to restore the spiritual life and philosophical foundations of the Church.