Wing Commander #3: Heart Of The Tiger by William R. Forstchen

Terran forces are pushed to the wall by the ever-encroaching Kilrathi hordes. The end seems very near–it is time for desperation measures. Against overwhelming odds, the humans try to launch a last desperate offensive against the Kilrathi homeworld. Once again, humanity’s last best hope is embodied in her flyers.
The unrelenting war against the hordes has taken its toll on the fatigued humans, and the Bantag horde’s latest siege has broken the Republic’s will to fight. Keane resigns his position in the Republic’s government when a peace parley is declared. Gathering the remaining veterans of the 35th Maine to his side, he plans a campaign that will take the Lost Regiment into the heart of the Bantag Empire to annihilate their ability to wage war once and for all. The outcome of this suicide mission will decide the fate of the human race on a world far from Earth.