Decimating an army has commonly meant killing off so many soldiers that the army is no longer an effective fighting force. However, there are actual numbers assigned to decimation.

Believe it or not, an army's own commanders are the ones who decide to decimate their army. In these terms it means to kill or execute one out of every ten soldiers. This usually happens after the non-commissioned officers are executed for incompetence.

During World War I the French army mutinied and refused to go "over the top" in attack; they did defend against German attacks. Although this happened at a particularly bloody battle, the mutiny was a long time coming, the result of years of bloody and wasteful tactics against a well-entrenched German army. The French troops were tired of being thrown at wire and machine gun nests in massive human wave attacks which cost thousands of lives. Small unit tactics had been successfully tried but the French commanders favored a more traditional (i.e. wasteful) tactic.

The French command executed all Non-Comms (Non-commissioned officers) and then shot every tenth soldier in an attempt to force the troops back into action. The tactic did not work; the soldiers realized that they had a better chance at one in ten with the decimation than they did against the German trenches where only one in ten would survive.

The political leadership of France relieved the high commanders of the army and replaced them. The troops went back to the front with new leadership and continued to fight.

Source: "The World Wars" as taught by Bob Welsh at Westminster College

Reply: If any information in my writeup is not factual, I apologize. It as been some time since I took the class and am recalling the information as it was presented to me (yes, I did pull out my class notes). As I remember, the records of the mutiny were sketchy, and I have heard various versions of the same events. The writeup below is clearly more detailed and cites various sources. My intention was simply to set the record strait about this commonly misused word. The example of the French Army was merely an illustration of the concept.
Thank you, Kung for clearing up this node, and setting me right again.

The Don't make shit up softlink that appeared at the bottom of this node indicates that some noders may have difficulty believing the above write-up, However while the write-up contains a certain amount of exaggeration it is essentially based on fact.

The writer is probably referring to the mutinies that occurred in the French Army after the Nivelle Offensive of April 1917.
General Robert Nivelle, the newly appointed Commander in Chief of French forces was determined to break the German line on the Western Front and mounted a major offensive on April 16. He confidently predicted he would overrun the German line within 48 hours. The Germans were heavily dug in however and French gains were minimal despite horrendous losses.

Despite this Nivelle refused to give in and continued to send French soldiers to their deaths until French units began to Mutiny. Soldiers being transported to the front refused to board trains and entire divisions refused to go into battle. It is said that at its height half the French Army was involved in the revolt.

At this point Nivelle was replaced by Henri Phillipe Petain who had a much better reputation for concern for the troops under his care. Petain used a carrot and stick approach to quell the mutiny. He stopped the offensive and decreed France would take a up a defensive position, he improved soldiers rations, living conditions and doubled their leave. However, he also made an example of those involved in the mutiny to show that authority was to be obeyed. He had ringleaders executed or sent to Devil's Island, and it was reported that in some rebellious units every tenth man was shot.

These tactics worked and by mid-June the mutinies were over.
