The Dragon Folk are Eusocial Creatures
Eusocial creatures, like ants or bees, are better suited for warfare than any other type of creature. For an average warrior or worker, there is a far stronger need to be willing to sacrifice ones self without a second thought than there is to try to survive or escape combat.
Dragon folk are such creatures. They live in huge hive complexes of genetically similar individuals, with each dragon folk single mindedly existing for the glory of their hive. Things like bravery or selflessness in combat are completely alien concepts to them. Dragon folk have trouble understanding why anybody would run away or try to save themselves. They don't understand individual glory or valor, and don't have a strong emotional attachment to their lives or the lives of their comrades. For most races, if you kill their best friend in front of them, they'll be distraught. Dragon folk will not only be completely unaffected, but they won't understand the concept of being emotionally affected by such an act.
Dragon folk are not stupid, of course. In the face of overwhelming odds, they will retreat in whatever manner they see to be most beneficial to the hive. They're expert tacticians, and understand that they have value to the hive. They're also not cold or emotionally distant to one another. They're friendly and gregarious, easily forming tight social bonds with one another. They also understand that they and all of their friends exist as part of the larger whole, and don't feel emotionally hurt at the loss of a friend in the service of the hive.
Soldiers and Workers
The two most common types of dragon folk are the soldiers and the workers. Both are effectively genderless, with reproduction being the domain of the queens and drones. Soldiers are huge, hulking dragon folk with thick armor who are well equipped for hauling heavy machinery or hacking down their enemies in melee combat. They've got sharp teeth and claws, redundant vital organs, they heal rapidly, and like most dragon folk, are completely fearless in combat. They also have exceptionally tactical minds, and make for devious military commanders. On the other hand, their minds typically fare poorly when presented with tasks outside of the military realm. They are interested in technologies and sciences that can help in war, but generally defer to workers to actually conduct the research involved. Historically, dragon folk armies were made primarily of soldiers, but with the advancement of technology placing high powered weapons in the hands of workers, the advantages of being a hulking combat brute with two hearts have lessened somewhat. Soldiers have prodigious appetites and grow quickly, but also have much shorter lifespans than most other dragon folk. Due to constant internal warfare between dragon folk hives, however, very few soldiers actually live long enough to die of natural causes.
Workers are smaller and lighter than soldiers, without the combat-specific adaptations that soldiers have like duplicate organs or claws. Dragon folk workers are generally nimble, hardy, and hard working. Intelligence in workers is similar to that found in humans, so far as ability to make scientific and mathematical discoveries is concerned. Cooperation is one of their greatest assets, with groups of workers working together seamlessly for the good of the hive. Workers are the most common members of society, and also make up what is effectively the ruling class in each hive. All bureaucrats and government officials are from the worker class, though in military matters, the soldiers are generally deferred to. Workers also have long lives, compared to most other dragon folk.
Due to their fearless nature, workers make for better soldiers than do members of most other races, though they fight without the single minded ferocity of the soldiers. All workers receive martial training, though almost none are full time soldiers.
Queens and Drones
The only exceptions to this are the dragon folk queens, who have a strong self preservation instinct. Dragon folk queens understand that they exist mostly for the purpose of laying thousands of eggs. They have no urge to protect those eggs, since that task is carried out by the workers. They are not generals or leaders, but they are consummate diplomats, socially interacting with other hives through their drones, which are the only hive members allowed to enter other hives.
Drones exist for the purpose of communicating and exchanging genetic information with other hives. They exist in far larger numbers than the queens, since walking into a potentially hostile enemy hive for diplomatic work or procreation can be quite dangerous. Like all other dragon folk, of course, they've evolved to be good at their job, and will do so fearlessly, even in the face of probable death. They're also good diplomats, and have evolved to be immune to torture. They're fairly incompetent at combat, however, and know this. While they'll selflessly walk into danger in the line of duty, they'll flee from combat itself. They and the other dragon folk see nothing strange about this.
Warfare among the dragon folk
Dragon folk live in huge city-like hives, which are in a state of almost constant low-level probing conflict with one another. Hives compete with one another for resources and influence, forming into military blocs that rise and fall based on the fortunes of their constituent hives. Dragon folk instictually view all sentient creatures not from their hive or closely related hives as enemies, so large alliances tend to be quite fragile. In this low-level state of combat, prisoners are regularly captured and exchanged back to their home hives in exchange for other resources. Dragon folk do not consider this to be 'war', as such, and fighting tends to be less lethal. In some dragon folk cultures, this low level combat is mostly ritualistic, with opponents sizing each other up in mock combat and imprisoning the perceived loser.
All out war occurs somewhat regularly, with multiple hives diving in to destroy weakened hives and then fight over their holdings. War among the dragon folk is merciless, and is carried out with the intent of slaughtering all the inhabitants of the hive in question, from infants to queens, as conversion of dragon folk to different hives is essentially impossible. In an all out war, prisoners are never taken or expected from the hive being exterminated, though prisoner capture and exchange takes place as normal between the overrunning hives.
This attitude towards warfare is carried to their conflicts with other races, which are similarly violent. Most of their enemies, however, do not grasp the nuances of the dragon folk combat society, so wars tend to be more of the all out variety.