One of the scriptural phrases intimately associated with Ascensiontide is that when our Lord ascended into heaven, "he led captivity captive…"
These words remind us that the passion, death, resurrection, and ascension of Christ make up one continuous event, the event which conquered sin and Satan. We should view this as the "great war" of all the ages.
In Gethsemane the enemy was met; on the Cross the battle was fought; in the Tomb Satan was defeated; and when our Lord ascended into heaven, he went as the victorious Warrior. His "prisoners of war" were all those things which keep us from having full communion with Almighty God.
This was the combat which has brought us peace - the captivity which has given us freedom in Christ.
Grant, we beseech thee, Almighty God: that like as we do believe thy Only Begotten Son our Lord Jesus Christ to have ascended into the heavens; so we may also in heart and mind thither ascend, and with him continually dwell; who liveth and reigneth with thee, in the unity of the Holy Spirit, ever one God, world without end. Amen.