Two good books concerning the Holy War that should be read.
1.) The Invisible War by Donald Grey Barnhouse.
2.) The Holy War by John Bunyan. (same Bunyan who wrote Pilgrims progress)
Quantrill
I have a better book to read, it's called the Holy Bible and teaches past, present and future Holy wars.
The first battle mention in scripture is found in Genesis 14:1-24. Shinar, Ellasar and Elam became known later in scripture as being Babylon, which is now modern day Iraq. These kings have always fought and taken captive Gods covenant people starting with Lot who was Abraham's nephew in whom Abraham took his army and fought against these four eastern kings and defeated them. This first battle was about controlling power, greed and monopoly on international trade (economics) as they tried to defeat everyone who opposed them as they took captive not only possessions from others, but also held them captive those who would not bow down to their false gods. As history repeats itself this same ruling Empire that has existed since the time of Abraham and going clear back to Nimrod and the Tower of Babel will also take place in the end of days when the beast rises out of the sea and gives power to the beast out of the earth who will exercise all the power of the first beast before him. The beast out of the earth will have ruling power over economics, political and a one order religion, Rev Chapter 13.
We know how history repeats itself as Jerusalem has been destroyed twice, besieged 23 times, attacked 52 times, and captured and recaptured 44 times as these eastern kings will always try to take posession of what God gave to Abraham through the covenant God made with him in Genesis 12:1-3 and all his generation after him. This will continue until the last day when Christ returns, John 6:40, as these four kings are that of the controlling power within the four nations Daniel speaks of in Daniel Chapter 7 with the last one that received a deadly wound, but the wound has been healed, Revelation 13:3. The four nations are: Babylonian Empire: Iraq (the lion), Medo, Persian Empire: Iran (the ribs of the bear), Grecian Empire: (Greece, Turkey, Syria, Egypt) four wings of the leopard, Roman Empire: (Iron represents the stronghold this nation had and still has). Daniel chapter 2 mentions the iron element of this empire that it to will be divided and broken as God will set up a kingdom that will never be destroyed.
The beast rises up out of the sea as the sea here is symbolic of people and nations as in a sea of humanity, Daniel Chapter 7:1-8; Revelation 17:15. The beast was given a mouth speaking great things and blasphemies and power was given unto him to continue for three and a half years which equals 1260 days, Daniel 7:25; 12:7; Revelation 11:2, 3. And it was given unto him to make war with the saints and to overcome them and power was given him over all kindred’s, and tongues, and nations as this beast is the same as the four eastern kings found in Genesis 14:1-24 and Daniel Chapter 7.
Notice the fourth king in Genesis 14:1 was king over many nations as Satan worked through him as well as the other three kings, Genesis 14:14:1. This is the same with the beast out of the earth, that is the son of perdition/last antichrist) that Satan works through who will try to devour all those of faith in God and His Son Christ Jesus, 2 Thessalonians 2:3-12; Rev 13:11-18. Daniel 7:24, 25 and another shall rise after them; and he shall be diverse from the first, He will think to change times and laws: and they shall be given into his hand until a time and times and the dividing of time (3 1/2 years). This fourth king (beast out of the earth) whose deadly wound came in 1798 and the wound was healed in 1929 is even now plotting for economic, political, military and religious control as he is the son of perdition who is the last false prophet (antichrist) who by lying signs and wonders will cause a great falling away from God, 2 Thessalonians 2:1-8 in as much as he can deceive the very elect if possible, Matthew 24:24.