Hammer's Slammers
1. Hammer's Slammers (1979)
2. Cross the Stars (1984)
3. At Any Price (1985)
4. Counting the Cost (1987)
5. Rolling Hot (1989)
6. The Warrior (1991)
7. The Sharp End (1993)
8. The Voyage (1993)
The Tank Lords (omnibus) (1986)
The Butcher's Bill (omnibus) (1998)
Caught in the Crossfire (omnibus) (1998)
Paying the Piper (2002)
The Complete Hammer's Slammers Vol. 1 (omnibus) (2005)
The Complete Hammer's Slammers Vol. 2 (omnibus) (2006)
The Complete Hammer's Slammers Vol. 3 (omnibus) (2007)

Starhunters
1. Men Hunting Things (1988)
2. Things Hunting Men (1988)
3. Bluebloods (1990)

World of Crystal Walls
1. The Sea Hag (1988)

Northworld
1. Northworld (1990)
2. Vengeance (1991)
3. Justice (1992)
Northworld Trilogy (omnibus) (1999)

General
1. The Forge (1991) (with S M Stirling)
2. The Hammer (1992) (with S M Stirling)
3. The Anvil (1993) (with S M Stirling)
4. The Steel (1993) (with S M Stirling)
5. The Sword (1995) (with S M Stirling)
6. The Chosen (1996) (with S M Stirling)
7. The Reformer (1999) (with S M Stirling)
8. The Tyrant (2002) (with Eric Flint)
The Conqueror (omnibus) (2003) (with S M Stirling)
Warlord (omnibus) (2003) (with S M Stirling)

War and Honor (with Gordon R Dickson, Christopher Stasheff and Chelsea Quinn Yarbro)
2. Blood and War (1993)

Reaches
1. Igniting the Reaches (1994)
2. Through the Breach (1995)
3. Fireships (1996)
The Reaches (omnibus) (2004)

ARC Riders (with Janet Morris)
ARC Riders (1995)
The Fourth Rome (1996)

Lord of the Isles
1. Lord of the Isles (1997)
2. Queen of Demons (1998)
3. Servant of the Dragon (1999)
4. Mistress of the Catacombs (2001)
5. Goddess of the Ice Realm (2003)
6. Master of the Cauldron (2004)

Belisarius (with Eric Flint)
1. An Oblique Approach (1998)
2. In the Heart of Darkness (1998)
3. Destiny's Shield (1999)
4. Fortune's Stroke (2000)
5. The Tide of Victory (2001)
6. The Dance of Time (2006)

Lt. Leary
1. With the Lightnings (1998)
2. Lt. Leary, Commanding (2000)
3. The Far Side of The Stars (2003)
4. The Way to Glory (2005)
5. Some Golden Harbor (2006)
6. When the Tide Rises (2008)
7. In the Stormy Red Sky (2009)

Crown of the Isles
1. The Fortress of Glass (2006)
2. The Mirror of Worlds (2007)
3. The Gods Return (2008)

Belisarius Omnibus (with Eric Flint)
1. Thunder at Dawn (2008)
2. Storm at Noontide (2009)
3. The Flames of Sunset (2009)

The Dragon Lord (1979)
Skyripper (1983)
The Forlorn Hope (1984)
Birds of Prey (1984)
Strangers and Lovers (1985)
Killer (1985) (with Karl Edward Wagner)
Active Measures (1985) (with Janet Morris)
Fortress (1986)
Ranks of Bronze (1986)
Lacey and His Friends (1986)
Bridgehead (1986)
Kill Ratio (1987) (with Janet Morris)
Vettius and His Friends (1989)
Target (1989) (with Janet Morris)
The Undesired Princess and the Enchanted Bunny (1990) (with L Sprague de Camp)
Surface Action (1990)
The Jungle (1991)
The Hunter Returns (1991) (with Jim Kjelgaard)
Old Nathan (1991)
Starliner (1992)
Tyrannosaur (1994)
Enemy of My Enemy (1995) (with Ben Ohlander)
Patriots (1996)
Redliners (1996)
All the Way to the Gallows (1996)
Seas of Venus (2002)
Other Times Than Peace (2006)

Time Safari (1982)
From the Heart of Darkness (1983)
The Military Dimension (1991)
The Military Dimension Mark II (1995)
The Warmasters (2002) (with Eric Flint and David Weber)
Grimmer Than Hell (2003)
Mountain Magic (2004) (with Eric Flint, Henry Kuttner and Ryk E Spoor)
Balefires (2007)

Crisis of Empire
1. An Honorable Defense (1988) (with Thomas T Thomas)
2. Cluster Command (1989) (with William C Dietz)
3. The War Machine (1989) (with Roger MacBride Allen)
4. Crown of Empire (1994) (with Chelsea Quinn Yarbro)

Heroes in Hell (with Janet Morris)
11. Explorers in Hell (1989)

Car Warriors
1. The Square Deal (1992)

Fleet (with Bill Fawcett)
1. The Fleet (1988)
3. Breakthrough (1989)
4. Sworn Allies (1990)
5. Total War (1990)
6. Crisis (1991)
Counterattack (1988)

Battlestation (with Bill Fawcett)
1. Battlestation: Book One (1992)
2. The Vanguard (1993)

A Century of Horror 1970-1979: The Greatest Stories of the Decade (1987) (with Martin H Greenberg)
Space Gladiators (1989)
A Separate Star: A Science Fiction Tribute to Rudyard Kipling (1989) (with Sandra Miesel)
Heads to the Storm (1989) (with Sandra Miesel)
Space Infantry (1989) (with Martin H Greenberg and Charles G Waugh)
The Eternal City (1989)
Space Dreadnoughts (1990) (with Martin H Greenberg and Charles G Waugh)
Armageddon (1998) (with Billie Sue Mosiman)
Foreign Legions (2001) (with Eric Flint and David Weber)
Dogs of War (2001)
The World Turned Upside Down (2005) (with Jim Baen and Eric Flint)