The devil has been shut out of heaven since He rebelled against God and was booted out.
The devil since then built up an occupation in the heavenlies. It was there in Daniel's day, being spoken of (Dan.10:20) regarding the prince of Greece taking over from the prince of Persia. The apostle Paul also speaks (Eph.6:12) of "the principalities, powers, rulers of the darkness of this world and wicked spirits in heavenly places."
When Jesus said (Lk.10:18), "I saw satan fall like lightening from heaven." He was speaking prophetically of the event recorded in Revelation 12:9.
The book of Revelation is the detailed account of what Daniel was told of concerning "the one week". Daniel 9:27 "He will make a covenant with many for one week." (a.k.a.- the 70th week of Daniel)
Daniel 9:26 speaks of there being seventy weeks and sixty-two weeks [shabua]. The Hebrew word is a period of seven.
The math is 70 X 7 = 490 and 62 X 7 = 434.. To apply days to either number wouldn't make sense regarding the prophecy but years would make sense.
So the prophecy is indicating that weeks are sevens which refers to years, which means that "one week" is a prophetic seven years.
In the Revelation the seven year Tribulation is divided into two 3.5 years.
For the first 3.5 years "the prince (or ruler) who shall come" (Dan.9:26), will propose that covenant with many. This prince is not Jesus. He said (Jn.5:43) to the Jews, "I have come in my Father's name, and you do not accept me; but if someone else comes in his own name, you will accept him." Jesus is thus saying that they will accept "a false messiah".
That will make possible for the Jews to build their Tribulation Temple. This is a reminder of Biblical, historical Cyrus who arranged that the Jews have permission to build up their previously destroyed, damaged Temple.
And so, during the first half of the Tribulation the Jews offer sacrifices as they did in the OT. They do it because it is commanded by the instructions of Moses a way to atone for their sins.
At the mid-point of the seven years that prince or lawless one will (Dan.9:27) "cause the sacrifices to cease."
That does not refer to the sacrifice of Jesus on the cross because after His ascension into heaven (Mk.16:19; Lk.24:51; Acts 1:9), the sacrifices continued to be offered up until (Lk.19:41-44) 70AD.
The only other way that the Bible speaks of that would cease the sacrifices is what Jesus said in Mat.24:15, "the abomination that causes desolation" because the Jews flee into the wilderness (Mk.13:14; Rev.12:6).
The apostle Paul also said in 2 Thes.2:4 that the lawless one would enter the Temple and take the seat and declare himself to be God.
This ironically is a similar repeat of what happened when Antiochus IV Epiphanes likewise desecrated the Temple.
From this it can be deduced that Dan.9:27 "the mid-week" is referring to the mid-point of the seven years Tribulation, at the end of the first 3.5 years and before the beginning of the second 3.5 years.
The war in the heavenlies (Rev.12:5-9) is when "the child" is being caught up to God. The phrase "caught up" is also found in 1 Thes.4:17.
So the war in heaven can only occur at the event of rapture. No such thing has happened yet.
Summary: Before the antichrist can go into the Temple and declare that he is God.. the Temple has to be built.. and before it can be built the antichrist has to be revealed (Rev.6:1) and then make a covenant with the many for one week.
It won't be until the midst of the one week (first 3.5 years) that the war in the heavenlies will happen, then satan and his demonic host will be kicked out of his place in the air and (Rev.12:8-9) be cast down to the earth.
So, it will be known that the end is in sight when he(the lawless prince) comes to make a covenant with many for one week.