[dave4420]

Electrics go down and don’t come back up -> petrol/gas stations stop working -> supply chains break down, including for food -> mass starvation.

Exactly how many people you expect to die will depend on your assumptions. Also on whether it occurs due to a CME (can expect humanitarian aid from the other side of the planet) or military action (other countries probably have more pressing concerns in this scenario).

[TeMPOraL]

> or military action (other countries probably have more pressing concerns in this scenario)

I'm starting to think that getting nuked would be preferable to a conventional attack disabling the national grid for prolonged duration. At least for those close to one of the impact sites it would be a faster and more pleasant way to go.

[dave4420]

For those a little bit further away from ground zero, I imagine a fatal dose of radiation would be slow and painful.

[TeMPOraL]

But would it be worse than starvation? I imagine that the two combined would hasten a victim's demise, too, which in this scenario might be desirable to the victim.