[Legbreaker]

In 1912 the US had 20,000,000 horses. That's twenty MILLION.
In 1968 that had dropped to seven million, mostly riding horses and not all that suitable to agriculture.
In 1997 using your figures, that had dropped to a bit over three million, with even less trained and/or suitable to heavy farm work.

Meanwhile, the US population was approximately 95 million in 1912 and in 1997 about three times that numer (271 million).

Even if the population is halved in November 97 and follow up strikes, etc, that's still about 1.5 times what it was in 1912 with a tiny fraction of draft animals available to pick up the slack on farms. I think it's clear petrochemicals along with every other conceivable power source would be of vital importance to have a hope in fending off even more deaths from famine.

Of course that's the US too. Europe, as mentioned, is in a MUCH worse state. Seems very likely the military would have to accept virtually no petrochem supply would be forthcoming. What little they received commanders would probably have to make some hard decisions about - try and maintain even a rudimentary mobile force, or grow food for themselves (very unlikely civilians production would even come close to providing what them themselves required, let alone essentially non-productive military).

I believe this is borne out by the extremely limited military actions detailed in the books for this early post nuke period. Seems likely the first year would have been absolutely horrific and those who survived would look back at it as a time of extreme and unrelieved hunger.
The second year might be a little better, if only because there were less mouths to feed and they had more of an idea of what they needed to do to survive.