In MILITARY Science Fiction, here are some I (Fittings Doc) would recommend:
"The Forever War" (1974 / 236 pages) by Joe Haldeman
Deals with the effect of time dilation, on those involved in an interstellar war.
(Won the Hugo and Nebula Awards.)
“Hammer's Slammers” (1979 / 274 pages) by David Drake ****
“The Tank Lords” (repackaged with some additional stories 1997 / 400 pages) by David Drake
(the first book of the "Hammer's Slammers" series)
“With the Lightnings” (1998) by David Drake ****
(the first book of the “Republic of Cinnabar Navy (RCN)”/ “Lt. Leary” series)
"Sten" (1982 / 279 pages) by Chris Bunch and Allen Cole
(the first book of "The Sten Chronicles")
Sten is orphaned and then recruited into the Eternal Emperor's "Mantis" covert intelligence corps.
"Dorsai" (1959 / 159 pages) by Gordon R. Dickson
(the first book of “The Childe Cycle”)
Deals with genetic drift and specialization, and there effects on humanity as a whole.
Nominated for the Hugo award.
“Dune” (1965 / 412 pages) by Frank Herbert
(the first book of the “Dune Series)
(Won the Hugo and Nebula Awards.)
"Warriors Apprentice" (1986 / 312 pages) by Lois McMaster Bujold
(the first book of "The Vorkosigan Saga")
(FOUR other books in the series Won Hugo Awards.)
After being genetically "damaged" by a bio weapon in his mother's womb, Miles Vorkosigan overcomes prejudice to claim his birthright.
"On Basilisk Station” (1993 / 448 pages) by David Weber ****
(the first book in the "Honor Harrington" series)
This Space Navy series has FEMALE lead character. Beyond the Technology of the spacecraft and weapons, the story revolves around interpersonal relationships with which you will be able to identify.
“Mutineers' Moon” (1991) by David Weber ****
(the first book in the “Dahak trilogy”)
“Prince of Sunset” (1998) by Steve White
(the first book in the “Prince of Sunset” series)
“The Last Legion” (1999) by Chris Bunch
(the first book of “The Last Legion” series – Space/Military)
“Ensign Flandry” (1966) by Poul Anderson
(the fist book, by internal chronology, of the “Terran Empire period of Dominic Flandry” series)
"The Regiment" (1987) by John Dalmas
(the first book of "The Regiment" series)
"The White Regiment" (1987) by John Dalmas
"The Regiment: A Trilogy" (omnibus of "The Regiment", "The White Regiment" and "The Regiment's War"), (2004 / 724 pages) by John Dalmas The planet Tyss has only one resource: soldiers.
They train the White Regiment from children of a non agressive planet who tend to see "war as play".
“Prince of Mercenaries” (1989) by Jerry Pournelle
(the first book of the “The Falkenberg's Legion” series)
“Legion Of The Damned” (1993 / 352 pages) by William C. Dietz
(the first book of the “Legion” series)
"Starship Troopers" (1959 / 263 pages) by Robert A. Heinlein
(won the Hugo Award 1960)
“The Rim of Space” (1961 / 226 pages) by A. Bertram Chandler
(first book of the “Rim World” / “John Grimes” series)
"Officer-Cadet" (1998) by Rick Shelley
(first book of the "Dirigent Mercenary Corps" series)
Lon Nolan's progression through the ranks of The Dirigent Mercenary Corps. Cheated out of his chance to serve in his home land's armed forces. He was given a second chance at a soldier's life, as a professional soldier on the colony world of Dirigent. Dirigent's sole industry is war.
“The Buchanan Campaign” (1995) by Rick Shelley
(first book of the “Second Commonwealth War” series)
“The Lost Fleet: Dauntless” (2006) by Jack Campbell (pseudonym for John G. Hemry)
(first book of “The Lost Fleet” series)
Two competing human space cultures clash.
“Stark's War” (2000) by John G. Hemry
(first book of the “Stark's War” series)
Rebellion on the moon.
"Sassinak" (1990) by Anne McCaffrey
(the first book of “The Planet Pirates trilogy”)
Has a FEMALE lead character.
“Once a Hero“ (1997) by Elizabeth Moon
(first book of the “Esmay Suiza” trilogy)
Another Space Navy series with a FEMALE main character.
Beyond the Technology of the spacecraft and weapons, the story revolves around a personal struggle for identify with which you will be able to identify.
“Old Man's War” (2005) / 320 pages) by John Scalzi
(first book of the “Old Man's War” series)
(Nominated for the Hugo Award)
“The Star Fox” (1965 / 208 pages) by Poul Anderson
(Nominated for a Nebula Award)
“Semper Mars” (1998 / 384 pages) by Ian Douglas (pseudonym for William H. Keith)
(first book of the “Heritage Trilogy”)
“March or Die” (1992 / 256 pages) by Andrew Keith and William H. Keith (aka Ian Douglas)
(first book of the “Fifth Foreign Legion” trilogy)
“Birth of Fire” (1987 / 229 pages) by Jerry Pournelle
“Not for Glory” (1983) by Joel Rosenberg
(first book about the “Metzadan Mercenary Corps”)