While the church fathers were far from monolithic in their atonement theology, the dominating idea seems to have been something along the lines of the Christus Victor model, albeit often combined with a ransom view, or some aspect of Jesus’s death as redemptive and generally salvific. It was often possible to combine Christus Victor and substitutionary atonement. Athanasius artfully combined the two together when writing about the incarnation:
The Word, as I said, being Himself incapable of death, assumed a mortal body, that He might offer it as His own in place of all, and suffering for the sake of all through His union with it, might bring to nought Him that had the power of death, that is, the devil, and might deliver them who all their lifetime were enslaved by the fear of death.
Calvin also regarded the cross as a divine victory. The French Reformer commented:
If we identify sin, death, and evil as that which believers are redeemed from, then regarding the cross as a redemptive victory enables us to construct a view of the atonement that is simultaneously catholic in breadth and Reformed in emphasis.
Finally, since as God only he could not suffer, and as man only could not overcome death, he united the human nature with the divine, that he might subject the weakness of the one to death as an expiation of sin, and by the power of the other, maintaining a struggle with death, might gain us the victory.… But special attention must be paid to what I lately explained, namely, that a common nature is the pledge of our union with the Son of God; that, clothed with our flesh, he warred to death with sin that he might be our triumphant conqueror.
 Athanasius, Incarnation, 4.20.
 Institutes 2.12.2–3. Calvin also wrote: “And so, by fighting hand to hand with the power of the Devil, with the horror of death, he won the victory over them and triumphed, so that now in our death we should not fear those things which our Prince has swallowed up” (Institutes 2.16.11). See Robert A. Peterson, Calvin’s Doctrine of the Atonement (Phillipsburg, NJ: Presbyterian & Reformed, 1983), 46–54.