A more thorough explanation:

A soldier's will is a type of will that is usually valid even if it doesn't follow the normal rules for making a will. This is because soldiers may not have access to a lawyer or witnesses when they are in active service. As long as the soldier was in service at the time the will was made, it is usually considered valid.

For example, if a soldier writes a letter to his family before going into battle, stating how he wants his property to be distributed if he doesn't come back, this can be considered a soldier's will. Even though it wasn't signed in front of witnesses or notarized, it can still be considered valid.

Another example is if a soldier makes an oral will to a fellow soldier while they are on the front lines. Even though there is no written record of the will, it can still be considered valid if the soldier who heard it can testify to its contents.