Why Marines Needed a Smaller Leonidas

Introduction

The Marine Corps did not need a smaller Leonidas simply because it preferred lighter equipment. It needed a different balance of capabilities. While the original Leonidas high-power microwave (HPM) system demonstrated the ability to disable multiple drones simultaneously, Marine expeditionary operations demand equipment that can move rapidly between temporary positions, operate with limited logistics support and deploy from light tactical vehicles rather than large fixed sites. The resulting Leonidas Expeditionary, developed through the Expeditionary Directed Energy Counter-Swarm (ExDECS) programme, represents an effort to preserve the core counter-swarm effect while dramatically reducing the size, weight and deployment burden of the system. [Epirus]epirusinc.comEpirusEpirus to Deliver Leonidas Expeditionary in Partnership…23 Sept 2024 — As part of the contract, Epirus will deliver a completed…

This shift reflects a broader reality of modern directed-energy weapons: battlefield usefulness is often determined as much by transportability and sustainment as by raw power. For Marines operating dispersed expeditionary forces, a powerful system that cannot move easily may be less valuable than a somewhat smaller system that can accompany the force wherever it goes. [DefenseScoop]defensescoop.commarines microwave weapon hpm epirus leonidas expeditionaryMarines to get new drone-killing microwave weapon…23 Sept 2024 — The high-power microwave weapon prototype, known as Leoni…

What Expeditionary Counter-Swarm Missions Require

Marine Corps operational concepts such as Expeditionary Advanced Base Operations (EABO) and stand-in forces emphasise small, distributed units operating from temporary locations that may be established and abandoned quickly. These forces are expected to remain mobile, avoid presenting large signatures and operate with limited infrastructure. At the same time, they face increasing threats from reconnaissance drones, loitering munitions and coordinated drone swarms. [Epirus]epirusinc.comEpirusEpirus to Deliver Leonidas Expeditionary in Partnership…23 Sept 2024 — As part of the contract, Epirus will deliver a completed…

That creates a difficult requirement for counter-drone systems. Traditional air-defence equipment often assumes access to established bases, larger vehicles or substantial support networks. Marine expeditionary units cannot always rely on those conditions. They require systems that can:

High-power microwaves are attractive because they offer a “one-to-many” effect, potentially disabling several drones within an engagement area at once. However, achieving that effect traditionally requires substantial power generation, cooling and supporting hardware. The challenge for ExDECS was therefore not merely to create another microwave weapon, but to make one compatible with expeditionary warfare. [Epirus]epirusinc.comNavy for…29 Apr 2025 — Leonidas Expeditionary was introduced in 2024 and is the latest addition to the company's suite of scalable hig…

How ExDECS Changed the Packaging Problem

The ExDECS programme effectively turned a technology problem into a packaging problem. The central question was not whether Leonidas could defeat drones; earlier variants had already demonstrated the viability of the microwave approach. The challenge was whether the capability could be condensed into a form suitable for Marine expeditionary operations. [DefenseScoop]defensescoop.comArmy awards $66M contract to Epirus for microwave…January 23, 2023 — 23 Jan 2023 — Army awards $66M contract to Epirus for…Published: January 23, 2023

Epirus repeatedly described Leonidas Expeditionary as a derivative of the broader Leonidas family that reduces size and weight while maintaining operational relevance for counter-swarm missions. The company states that the design uses its scalable HPM architecture to create a compact, manoeuvrable system capable of operating from lighter platforms. [Epirus]epirusinc.comEpirusEpirus to Deliver Leonidas Expeditionary in Partnership…23 Sept 2024 — As part of the contract, Epirus will deliver a completed…

Several design choices illustrate this shift:

• The system was designed to integrate with light tactical vehicles and companion trailers rather than requiring larger dedicated platforms. [Epirus]epirusinc.comNavy for…29 Apr 2025 — Leonidas Expeditionary was introduced in 2024 and is the latest addition to the company's suite of scalable hig…
• It was tailored for Marine Corps Low Altitude Air Defense (LAAD) and Ground Based Air Defense missions rather than fixed-site protection. [Epirus]epirusinc.comNavy for…29 Apr 2025 — Leonidas Expeditionary was introduced in 2024 and is the latest addition to the company's suite of scalable hig…
• It emphasised modularity and scalability so that deployment options could vary according to mission requirements. [Epirus]epirusinc.comEpirusEpirus to Deliver Leonidas Expeditionary in Partnership…23 Sept 2024 — As part of the contract, Epirus will deliver a completed…
• It was designed for integration with existing Marine command-and-control architectures and expeditionary air-defence networks. [Military Embedded Systems]militaryembedded.comFeatured CompaniesMilitary Embedded SystemsDirected energy counter-swarm system under development…Epirus is scheduled to deliver a completed ExDECS HPM…

The result was not a simple downsized copy of Leonidas. It was a version optimised around Marine operational constraints, where the ability to arrive, set up and relocate quickly may determine survivability.

Why Transportability Matters as Much as Power

A recurring misunderstanding about directed-energy weapons is that maximum power output is always the dominant performance metric. For expeditionary forces, transportability can be equally important.

A larger microwave system may provide greater engagement capacity, but it also creates challenges. Bigger systems require larger vehicles, more fuel, additional support equipment and more predictable operating locations. Those requirements can conflict directly with Marine concepts that emphasise dispersal, concealment and rapid movement. [DefenseScoop]defensescoop.commarines microwave weapon hpm epirus leonidas expeditionaryMarines to get new drone-killing microwave weapon…23 Sept 2024 — The high-power microwave weapon prototype, known as Leoni…

Leonidas Expeditionary reflects a recognition that a counter-swarm weapon only contributes to force protection if it can accompany the force. A microwave system left behind because it is too difficult to move provides no protection to a relocated expeditionary base. By contrast, a somewhat smaller system that can travel with Joint Light Tactical Vehicles, trailers and rapidly deployed air-defence elements remains available wherever the threat emerges. [Epirus+2Military Embedded Systems]epirusinc.comEpirusEpirus to Deliver Leonidas Expeditionary in Partnership…23 Sept 2024 — As part of the contract, Epirus will deliver a completed…

This trade-off is particularly important because drone threats themselves are highly mobile. Small unmanned aircraft can appear with little warning, forcing defenders to shift locations frequently. Expeditionary units therefore need defensive systems whose mobility approaches that of the forces they protect.

The Risks of Shrinking a Directed-Energy Weapon

Reducing size and weight is not automatically beneficial. Miniaturisation introduces risks and trade-offs that help explain why ExDECS is being evaluated through experimentation rather than immediate large-scale procurement. [Epirus]epirusinc.comNavy for…29 Apr 2025 — Leonidas Expeditionary was introduced in 2024 and is the latest addition to the company's suite of scalable hig…

Potential concerns include:

• Power availability: Smaller platforms generally provide less electrical power than larger vehicles or fixed installations.
• Thermal management: Compact systems have less room for cooling equipment.

The Marine Corps appears willing to accept these challenges because the alternative—a highly capable system that cannot support expeditionary manoeuvre—would undermine the service’s operating concepts. The programme therefore reflects a deliberate prioritisation of operational flexibility over the pursuit of maximum system scale.

What the Marine Variant Reveals About Directed-Energy Warfare

Leonidas Expeditionary demonstrates an important trend in directed-energy development. The question is no longer only whether microwave weapons work against drone swarms. Increasingly, the question is whether those weapons can be packaged into forms that match how military units actually operate. [Epirus]epirusinc.comNavy for…29 Apr 2025 — Leonidas Expeditionary was introduced in 2024 and is the latest addition to the company's suite of scalable hig…

For the Marine Corps, the answer required shrinking the system. ExDECS emerged because expeditionary forces needed a counter-swarm capability that could move with dispersed units, integrate with light vehicles and function in austere environments without the support structure normally associated with larger directed-energy systems. [Epirus+2Military Embedded Systems]epirusinc.comEpirusEpirus to Deliver Leonidas Expeditionary in Partnership…23 Sept 2024 — As part of the contract, Epirus will deliver a completed…

In that sense, the most significant innovation of Leonidas Expeditionary may not be the microwave effect itself. It is the attempt to make that effect compatible with the realities of expeditionary warfare, where mobility, logistics and survivability are often as decisive as firepower. [Epirus]epirusinc.comEpirusEpirus to Deliver Leonidas Expeditionary in Partnership…23 Sept 2024 — As part of the contract, Epirus will deliver a completed…

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Endnotes

1. Source: defensescoop.com
   Title: marines microwave weapon hpm epirus leonidas expeditionary
   Link: https://defensescoop.com/2024/09/23/marines-microwave-weapon-hpm-epirus-leonidas-expeditionary/
   Source snippet

   Marines to get new drone-killing microwave weapon...23 Sept 2024 — The high-power microwave weapon prototype, known as Leoni...

2. Source: defensescoop.com
   Link: https://defensescoop.com/2023/01/23/microwave-weapon/
   Source snippet

   Army awards $66M contract to Epirus for microwave...January 23, 2023 — 23 Jan 2023 — Army awards $66M contract to Epirus for...

   Published: January 23, 2023

3. Source: defensescoop.com
   Title: british troops test drone zapper radio frequency directed energy weapon rfdew
   Link: https://defensescoop.com/2024/12/23/british-troops-test-drone-zapper-radio-frequency-directed-energy-weapon-rfdew/
   Source snippet

   British troops test new [drone swarm]({{ 'swarm-limits/' | relative_url }}) zapperDec 23, 2024 — The British military recently conducted its first-ever successful, live-fire tes...

4. Source: epirusinc.com
   Link: https://www.epirusinc.com/press-releases/epirus-to-deliver-leonidas-expeditionary-in-partnership-with-onr-jco-usmc-expanding-high-power-microwave-product-suite
   Source snippet

   EpirusEpirus to Deliver Leonidas Expeditionary in Partnership...23 Sept 2024 — As part of the contract, Epirus will deliver a completed...

5. Source: cuashub.com
   Title: epirus announces 5 5 million u s navy contract for hpm system
   Link: https://cuashub.com/en/content/epirus-announces-5-5-million-u-s-navy-contract-for-hpm-system/
   Source snippet

   Epirus announces $5.5 million U.S. Navy contract for HPM...Sep 26, 2024 — Epirus has secured a $5.5 million contract from the U.S. Navy...

6. Source: epirusinc.com
   Link: https://www.epirusinc.com/press-releases/epirus-delivers-exdecs-hpm-prototype-to-u-s-navy-for-marine-corps-counter-drone-swarm-capability
   Source snippet

   Navy for...29 Apr 2025 — Leonidas Expeditionary was introduced in 2024 and is the latest addition to the company's suite of scalable hig...

7. Source: militaryembedded.com
   Title: Featured Companies
   Link: https://militaryembedded.com/unmanned/counter-uas/directed-energy-counter-swarm-system-under-development-for-us-marine-corps
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   Military Embedded SystemsDirected energy counter-swarm system under development...Epirus is scheduled to deliver a completed ExDECS HPM...

8. Source: asdnews.com
   Link: https://www.asdnews.com/news/defense/2024/09/24/epirus-deliver-leonidas-expeditionary-partnership-with-onr-jco-usmc-expanding-highpower-microwave-product-suite
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   Epirus to Deliver Leonidas Expeditionary in Partnership withSep 24, 2024 — Epirus announced today the introduction of Leonidas Expedition...

9. Source: Wikipedia
   Title: Epirus Leonidas
   Link: https://en.wikipedia.org/wiki/Epirus_Leonidas
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   Epirus LeonidasThe Leonidas Expeditionary Directed Energy Counter-Swarm (ExDECS) was unveiled in September 2024 as a small version for...

   Published: September 2024

10. Source: facebook.com
    Title: epirus leonidas expeditionary directed energy for counter swarm exdecs hpm
    Link: https://www.facebook.com/NextGenPHDef/posts/-epirus-leonidas-expeditionary-directed-energy-for-counter-swarm-exdecs-hpm/1024439542811629/
    Source snippet

    Leonidas will integrate with the US Marine Corps command...

11. Source: aresdifesa.it
    Link: https://aresdifesa.it/epirus-consegnera-leonidas-expeditionary-al-usmc/
    Source snippet

    Epirus consegnerà Leonidas Expeditionary al USMC25 Sept 2024 — Nell'ambito del contratto, Epirus consegnerà un sistema ExDECS HPM complet...

12. Source: x.com
    Link: https://x.com/epirus/status/1917209953992913317
    Source snippet

    EpirusWe're announcing the delivery of an Expeditionary Directed Energy Counter-Swarm (ExDECS) prototype to @NSWCDD to support counter-dr...

13. Source: x.com
    Link: https://x.com/nex_def/status/1917481109153275944
    Source snippet

    Epirus Delivers ExDECS Directed Energy Counter-Drone...30 Apr 2025 — ExDECS is derived from Epirus' Leonidas Expeditionary system and is...

14. Source: linkedin.com
    Link: https://www.linkedin.com/posts/epirus_to-kick-offmodern-day-marine-were-announcing-activity-7322973934394527744-2K_u
    Source snippet

    Epirus delivers ExDECS prototype to support counter-...ExDECS, a derivative of Leonidas Expeditionary, leverages Epirus' scalable energy...

Additional References

1. Source: linkedin.com
   Link: https://www.linkedin.com/posts/epirus_exclusive-marines-new-exdecs-microwave-activity-7244016981643862020-aOye
   Source snippet

   Exclusive: Marines New 'ExDECS' Microwave Weapon To..."Marine expeditionary forces are likely to be attacked by large numbers of such dr...

2. Source: unmannedairspace.info
   Link: https://www.unmannedairspace.info/counter-uas-systems-and-policies/us-marine-corps-takes-delivery-of-epirus-counter-drone-swarm-system/
   Source snippet

   US Marine Corps takes delivery of Epirus counter-drone...Epirus announced on April 29 that it has provided an Expeditionary Directed Ene...

3. Source: facebook.com
   Link: https://www.facebook.com/NSWCCrane/posts/nswc-crane-has-developed-the-drone-killer-cartridge-dkc-a-new-cost-effective-amm/1331850772319474/

4. Source: maritimefairtrade.org
   Link: https://maritimefairtrade.org/marines-unveil-new-microwave-weapon-to-counter-drone-threats-in-expeditionary-operations/
   Source snippet

   Marines Unveil New Microwave Weapon to Counter Drone...Dec 10, 2025 — Epirus is set to deliver a new drone zapper, known as the Leonidas...

5. Source: everythingrf.com
   Link: https://www.everythingrf.com/news/details/21275-us-military-demonstrates-high-powered-microwave-system-to-counter-drone-swarms
   Source snippet

   Navy and Marine Corps are also testing a related system known as ExDECS (Expeditionary Directed Energy Counter-Swarm), developed...Read...

6. Source: twz.com
   Title: marines get their first high power microwave weapon for taking on drone swarms
   Link: https://www.twz.com/land/marines-get-their-first-high-power-microwave-weapon-for-taking-on-drone-swarms
   Source snippet

   The War ZoneMarines Get Their First High Power Microwave Weapon...29 Apr 2025 — Leonidas Expeditionary was introduced in 2024 and is the...

7. Source: youtube.com
   Link: https://www.youtube.com/watch?v=bXXCK6gjSfg
   Source snippet

   ExDECS: High-Power Microwave System Delivered to USMC... Leonidas Expeditionary, is a mobile high-power microwave capability for counter...

8. Source: breakingdefense.com
   Title: defense tech company epirus delivers counter drone swarms to navy
   Link: https://breakingdefense.com/2025/04/defense-tech-company-epirus-delivers-counter-drone-swarms-to-navy/
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   Defense tech company Epirus delivers counter-drone...Apr 29, 2025 — MODERN DAY MARINE 2025 — Defense tech contractor Epirus today announ...

9. Source: acuitypartnersnyc.com
   Title: U S Marines ready to fry enemy drone swarms with new Epirus
   Link: https://acuitypartnersnyc.com/us-marines-ready-to-fry-enemy-drone-swarms-with-new-epirus-exdecs-microwave-weapon-system/
   Source snippet

   US Marines ready to fry enemy drone swarms with new Epirus...May 1, 2025 — It is a high-power microwave capability designed to fend off...

   Published: May 1, 2025

10. Source: realcleardefense.com
    Title: the marine corps new microwave drone swarm killer 1107197
    Link: https://www.realcleardefense.com/2025/04/30/the_marine_corps_new_microwave_drone_swarm_killer_1107197.html
    Source snippet

    The Marine Corps' New Microwave Drone Swarm KillerApr 30, 2025 — The ExDECS system is a derivative of the Leonidas system, using high-pow...