It was to make war on God's saints

The Christian Martyr's Last Prayer by Jean-Leon Gerome
Public Domain https://commons.wikimedia.org/wiki/File:The_Christian_Martyrs_Last_Prayer.jpg

I was watching; and the same horn was making war against the saints, and prevailing against them (Daniel 7:21).

Throughout history, the great wars of Europe were fought on religious grounds. The Protestants of Europe were relentlessly persecuted by Rome. Europe was plunged into the Thirty Years’ War with the sole purpose of destroying the Protestant Reformation.

The Waldenses, Albigenses, and Huguenots were relentlessly persecuted, and the Inquisition ordered the cruelest of punishments to be executed by the princes of Europe upon all those who refused to bow to the supremacy of Rome. In 1200, AD Pope Innocent III ordered the king of France to exterminate the Albigenses because they refused to accept the papal teachings and regarded the Bible as the ultimate Word of God. Historians D'Augbigné and Wylie say that more than a million of these innocent people were massacred in one single campaign.

John Calvin, in a letter to Emperor Charles V, wrote this:

I deny that See to be...the vicar of Christ, who, in furiously persecuting the gospel, demonstrates by his conduct that he is Antichrist.ⁱ

In the 13^th century, St. Thomas Aquinas said that convicted heretics should be put to death just as surely as other criminals, because they were counterfeits. In a 1912 Catholic magazine we read this:

You cannot excite any piety in our souls by whining accounts of Catholic atrocities...We have never written a line in extenuation or palliation of the Inquisition. We never thought it needed a defence.ⁱⁱ

The church historian Philip Schaff makes this comment:

So far as we know, the popes never uttered a word in protest against the inhuman measures which were being practised by the Spanish Tribunals.ⁱⁱⁱ

The historian Lecky says this:

The Church of Rome has shed more innocent blood than any other institution that has ever existed among mankind.^iv

The little horn power was thus to be a persecuting power that would war against God's people, and have success against them.

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i. John Calvin, Tracts Relating to the Reformation Volume 1.

ii. Western Watchman (November 1912).

iii. Philip Schaff, History of the Christian Church Volume 5 (New York: Charles Scribner and Co., 1870): 280.

iv. W. E. H. Lecky, History of the Rise and Influence of the Spirit of Rationalism in Europe Volume 2 (London: Longmans, Green, and Co., 1866): 35.