So, is it 25,000?

I hate to keep harping on this…..but I do believe in reasonable estimates of opposing forces strength and losses. I am not sure we are doing that.

  1. The U.S. claimed in August that there were 19,000 – 25,000 ISIL:Islamic State strength estimates
    1. I don’t believe I have seen strength estimates from before this time that is more than 25,000: Global Security
    2. About half were in Iraq.
  2. The U.S. now claims there are 12,000 to 15,000 ISIL: white-house-isis-down-to-12000-15000-battle-ready-fighters
    1. This includes 3,000 to 5,000 in Mosul: War updates
  3. The U.S. claims were have killed 50,000 in the last two years: Over 50000 killed
    1. Including 25,000 in the last 11 months: pentagon-counts-isil-dead-refuses-discuss-them
    2. 25,000 – 50,000 = 15,000…meaning they recruited 40,000 new fighters in the last two years?
  4. The U.S. claims were have attrited 75% of ISIL: US-Officials-Say-ISIS-Has-12-000
    1. 15,00 times 4 = 60,000…meaning working backwards this was the ISIL strength….or this includes the 40,000 new recruits added to a strength originally equal to 25,000? This math actually works, if you accept the figure of 40,000 new recruits.
    2. Of course, this is exterminating and replacing the entire ISIL force each year for two years in a row. Can’t really recall the historical president for this.
  5. The UK estimates we have killed 25,000 ISIL: uk-us-number-isis-fighters-killed
    1. This seems more reasonable.

Of course, part of the problem is that ISIL and every other insurgency movement out there does not consists only of full-time fighters. For example (see America’s Modern Wars: Chapter 11: “Estimating Insurgent Force Size”), looking at some the insurgent strength estimates from Vietnam, Cabanas (Mexico) and Shining Path (Peru), we came up with some rules of thumb for determining the mix of insurgents (see page 120):

  1. Full-time insurgents make up 10 to 20% of the force.
  2. Full-time and part-time insurgents are 20 to 50% of the force.
  3. Casual insurgents are 40 to 80% of the force.

This was based on a very limited selection of marginal data and of course, may not be relevant to ISIL, as they have developed a more conventional-like force structure. But, it does bring up the issue that most insurgencies are not only full-time committed fighters, but lots of people that only sometimes active (often regional), and a large collection of people that are only occasionally active (and may become inactive if things are not going well). Also, many of the insurgents are “support personnel” vice fighters. It is an issue that I don’t believe I have seen anyone else attempt to deal with analytically. Our efforts were only preliminary.

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Christopher A. Lawrence
Christopher A. Lawrence

Christopher A. Lawrence is a professional historian and military analyst. He is the Executive Director and President of The Dupuy Institute, an organization dedicated to scholarly research and objective analysis of historical data related to armed conflict and the resolution of armed conflict. The Dupuy Institute provides independent, historically-based analyses of lessons learned from modern military experience.
Mr. Lawrence was the program manager for the Ardennes Campaign Simulation Data Base, the Kursk Data Base, the Modern Insurgency Spread Sheets and for a number of other smaller combat data bases. He has participated in casualty estimation studies (including estimates for Bosnia and Iraq) and studies of air campaign modeling, enemy prisoner of war capture rates, medium weight armor, urban warfare, situational awareness, counterinsurgency and other subjects for the U.S. Army, the Defense Department, the Joint Staff and the U.S. Air Force. He has also directed a number of studies related to the military impact of banning antipersonnel mines for the Joint Staff, Los Alamos National Laboratories and the Vietnam Veterans of American Foundation.
His published works include papers and monographs for the Congressional Office of Technology Assessment and the Vietnam Veterans of American Foundation, in addition to over 40 articles written for limited-distribution newsletters and over 60 analytical reports prepared for the Defense Department. He is the author of Kursk: The Battle of Prokhorovka (Aberdeen Books, Sheridan, CO., 2015), America’s Modern Wars: Understanding Iraq, Afghanistan and Vietnam (Casemate Publishers, Philadelphia & Oxford, 2015), War by Numbers: Understanding Conventional Combat (Potomac Books, Lincoln, NE., 2017) , The Battle of Prokhorovka (Stackpole Books, Guilford, CT., 2019), The Battle for Kyiv (Frontline Books, Yorkshire, UK, 2023), Aces at Kursk (Air World, Yorkshire, UK, 2024), Hunting Falcon: The Story of WWI German Ace Hans-Joachim Buddecke (Air World, Yorkshire, UK, 2024) and The Siege of Mariupol (Frontline Books, Yorkshire, UK, 2024).
Mr. Lawrence lives in northern Virginia, near Washington, D.C., with his wife and son.

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