SWG, you covered the physical development of these soldiers, and their military training, but you neglected to describe their emotional growth. Humans, even cloned ones, have emotions unless the genetic altering affected this too. What the limits on this would be is unknown, since emotional reactions to stimuli has been part of human evolution (along with all major primates, canines, equines, and so on) for millions of years. Emotions are so connected to our (at this point I started writing in medical terms, but decided to be generalized. If you want specifics, let me know) bodily functioning that eliminating emotions altogether would probably be impossible IF you wanted to still call the clones "humans".
So, I am postulating that these clones can feel emotions, and were given some type of training that allowed these emotions to be manipulated (otherwise, why have "brothers" and "sisters" as the lab techs imprint them). Now, it may be possible to train a soldier in a year, and with accelerated growth produce a full size mature human body, but it takes years to learn to master the emotions. The brain is fully developed for years before a human is considered emotionally mature. Most current soldiers probably wouldn't be considered as emotionally mature by a psychologist, let alone someone who is only chronologically five or six.
So, without your postulating special emotional training and/or brainwashing, what you have are children in soldiers bodies who would at this point be suffereing from Post Traumatic Stress Disorder (formerly called battle fatigue, and before that, shell shock). It affects different people in different ways, and some of these ways are extreme. In normal human times, some soldiers go beserk, killing people seemingly at random. This is fairly rare, but the clones are children, and they have their own pathology, which is much more outwardly destruction than the way mature humans handle this with inward destruction (depression, fatigue, suicide, alienation, neurological damage). Since at least a third of normal soldiers contract PTSD, I have to figure that the clones will be suseptible to this disease too. Being emotionally children they will have a larger rate of infection.
The many ways the clones can manifest their symptoms are interesting to contemplate. Some, the most violent cases, will go on killing sprees, killing indiscriminately. Some, will stop functioning, sit down and stop eating. Many will wander like zombies, committing random acts of destruction, or targeted acts of destruction, much like a motorcycle gang stereotype. Some will rebel against their former leaders, and some will insist on continuing the attack on the enemy, no matter what. Many will take drugs to numb the emotional angst if they are available. Generally as a group they will be abusive, whether intentionally or not, directed inwardly or outwardly, and exhibit erratic behaviour.
Plus, since they have matured beyond physical puberty, they have the emotional equipment necessary to form strong sex/romance based relationships with other soldiers. The death of a romance partner to an emotionally immature person can cause PTSD all by itself, much less compounded with warfare. It is more likely to push someone totally over the edge into insanity than almost anything else. Since some of the others are brothers and sisters, I assume you are breaking them into small enough groups for this to be meaningful. Family member deaths also contribute to PTSD and give an extra push towards insanity.
So, that is my conclusion, they all end up crazy at the very least. I think a clone's life would be terrible and a waste of time and effort. It would be better to surrender to the enemy than to be the kind of person that would create that kind of misery. After all, this is Nuclear Age. It is never going to be impossible to just wipe everybody out, so their enemies would have already killed them if that was the point of the war. But the point of your war is to make the enemy surrender, or you would just nuke them instead of sending out cloned soldiers.
