|Tech Base||Inner Sphere|
|Armor||Regulas Basic (Primitive Armor)|
|Engine||Hermes 235 (Primitive) Fusion Engine|
|Communications System||Barret 4000|
|Targeting Tracking System||Wassat Watchdog W100|
Designed in 2470 but only entering production in 2500, the Ostwar was technologically primitive compared to other 'Mech designs developed in the Terran Hegemony at the time, forcing the Terran based firm to sell it to other nation states. Produced until the start of the Reunification War, the Ostwar would enjoy moderate success in the Capellan Confederation and the Free Worlds League, buying Ostmann the time and funding to build more advanced designs such as its successful Ostroc and Ostsol. To save on costs, many of these later designs shared similar and compatible parts with the more primitive Ostwar, with the design becoming extinct in the early Succession Wars, stripped for parts to maintain the more modern designs after the destruction of the Ostmann plant on Terra.
One of the many ancient designs revived thanks to the Hegemony Memory Core, the new independent Principality of Regulus's desperate need for BattleMechs during the Jihad saw them convert the Harmony MetalWorks IndustrialMech factory to production of the primitive 2M, with Ronin Incorporated building a new assembly line for the modern 3M after that conflict concluded.
Harmony MetalWorks and Ronin were not the only companies to produce Ostwars during the Jihad; other companies such as Osaka Heavy Metrics, a Draconis Combine IndustrialMech manufacturer, converted their existing lines to produce the Ostwar amongst other RetroTech designs from their factories on Togura and Philadelphia.
The Ostwar has a host of primitive and heavier technologies throughout its design such as its primitive cockpit. Constructed using a primitive eleven-ton Hermes 235, the underpowered engine limited the Ostwar to a top speed of 54 kph, while seventeen and half tons of Primitive Armor provides far less protection than modern armor materials.
Weapons and Equipment
The 2M Ostwar was armed with a twenty-tube Doombud Long Range Missile launcher for its long range attacks. In close range, the 'Mech was armed with two four-tubed Shannon SH-40 Short-Range Missile launchers in each of its paddle shaped forearms. It also mounted two Martell Medium Lasers mounted on the left torso. The 'Mech carried three tons of ammunition for the LRM rack, while carrying a ton of SRM ammunition in its left arm.
- An updated version of the primitive Ostwar developed in 2620, this variant carries 12 tons of standard BattleMech armor and a modern cockpit. The chassis has been upgraded to use Endo Steel, while an XL Engine increases the Ostwar's ground speed to 84 km/h. Eighteen double heat sinks dissipate the heat from three ER Large Lasers and twin SRM-6 launchers. BV (2.0) = 1,638
- The modern 3M version built at Ronin Incorporated's facility on Wallis in 3075, replaced all its components with advanced technology. Powered by a standard Hermes 260 Fusion engine, which increased the 'Mech's top speed by 10 kph, the chassis was protected by eleven tons of light ferro-fibrous armor and CASE mounted in both side torsos. Swapping the standard SRM racks for more advanced and ammo-efficient Shannon SH-47 Streak SRM-4 launchers and standard Medium Lasers for modern Diverse Optics ER Medium Lasers, with the LRM-20 launcher enhanced with Artemis IV FCS.  BV (2.0) = 1,557
- Colonel Michelle Ryan - Princess of Principality of Regulus and commander of 1st Regulan Hussars in the late 3060s and early 3070s. She was noted for receiving an Ostwar as a gift on her wedding day from her husband, Prince Titus Cameron-Jones.
- Jihad Hot Spots: 3076, pp. 116-117, "OWR-2M Ostwar"
- Objectives: Free Worlds League, p. 12
- Objectives: Free Worlds League, p. 14
- Objectives: Draconis Combine, p. 4
- Objectives: Lyran Alliance, p.4
- Objectives: Capellan Confederation, p. 18
- MUL online data for the Ostwar
- Experimental Technical Readout: Primitives, Volume 1, p. 6, "OWR-2M Ostwar"
- Technical Readout: 3085 Supplemental, p. 34, "SKU-197 Sokuryou SurveyMech"
- MUL online data for the Ostwar OWR-2Mb variant
- Record Sheets: 3085 Unabridged - The Cutting Edge, p. 137
- MUL online data for the Ostwar OWR-3M variant
- Technical Readout: 3085, pp. 90-91, "OWR-3M Ostwar"
- Record Sheets: 3085 Print Edition, p. 78
- Jihad Hot Spots: 3076, p. 28, "Ryan receives an Ostwar from her husband in May, 3075"