I am trying to find a book I read 30 or more years ago.
It was sci-fi and included space battles. I think they were between Earth’s humans and aliens but I’m not sure. I seem to think the humans won the final battle and war.
A new development was an 'Uncertainty Drive' with up to four or five levels of uncertainty that could be used to power rocket motors and beam weapons. Energy could be wantonly stored in tanks of mercury (Hg) for controlled (or self destructive rapid) release.
The drive name may have been some other but equally non-descriptive term but it was not the Infinite Improbability Drive from the Hitchhikers Guide to the Galaxy series.
I recall one of the ships was sacrificed by targeting the mercury storage tank with the on-board beam weapon.