This book starts a few years after the last one and despite the jump forward in time the planet Mars remains a stalemate between the human and Lanky forces. Humanity has established control of the skies above Mars but no matter how many Lankies are killed there always seems to be more of them. The human forces on Mars are wearing down every day as both ships and personnel are succumbing to battle fatigue and Andrew Grayson knows that humanity will not win this war of attrition. We continually rush new recruits into service aboard ships that are well past their prime but eventually the Lankies will get reinforcements and the house of cards will come tumbling down. This is unless we find a way to change the game...
The fifth book of the Frontlines series brings the story to a turning point for mankind. The first four books have seen humanity dominated by the alien Lankies, losing battle after battle, and abandoning every human planet except for Earth. Even then, the relentless attacks coming from the Lanky inhabited planet of Mars have caused humanity to barely maintain a hold on Earth. With our existence on the brink, the only option left is to go "all in" and launch an offensive to reclaim our solar system. Gathering up the scraps of the space fleet to attack Mars is a desperate play, but there are no other alternatives left.
Chains of Command picks up the story about one year after the end of Angles of Attack and Earth is still hanging on. Andrew Grayson finds himself training new recruits to backfill the depleted ranks of the spaceborne infantry but it is obviously too little too late. The Lankies retain control of Mars and regularly send siege ships toward Earth. The rag tag remnants of the NAC and SRA space fleets are barely able to repel them and every encounter is successful by only the slimmest of margins. Unfortunately, mankind knows it is losing the overall war of attrition and the status quo is unsustainable. This leaves only two choices available for regaining our solar system and they both involve attacking Mars. Take a chance and launch the assault now with what remains of the space navy or risk a blind raid in an attempt to recover the modern warships that were taken when the former NAC military and political leadership jumped away leaving everyone else behind to die.
Things have gone to hell for humanity. We have been driven back time and time again by the Lankies and we have no colonies left beyond 30 light years from Earth. As we set up defenses on the new border the Lankies suddenly jump all the way to our solar system and deal us a crushing blow by taking Mars. This wipes out the majority of our fleet and effectively cuts off our remaining colonies from Earth. Staff sergeant Andrew Grayson is now stranded on the colony moon of New Svalbard along with a small task force of ships and little food. Caught between a rock and a hard place Andrew knows they will all starve to death if they stay where they are but they would be blindly jumping into an unwinnable space battle if they try to go home.
For five years now humanity has been falling back. Although we have had limited success in ground skirmishes against the Lankies we have lost every single space battle against them. Colony world after colony world has fallen and their siege ships appear to be indestructible. Once they arrive at a planet they are able to land troops and terraform it to their needs quickly and efficiently. Despite this harsh reality, the North American Commonwealth and the Sino-Russian Alliance remain bitter enemies and they continue to fight against each other over the colony planets that do remain under human control. Even Earth itself has deteriorated as the two-front war sucks away all the resources and civil unrest has become the norm.
The Frontlines series introduces us to a bleak future that offers little hope to those born in the overcrowded cities of the North American Commonwealth. Most large American cities are now government run slums called PRCs (Public Residence Clusters) and this is the life Andrew Grayson is born into. Andrew and his parents live on welfare and since he has no intention of inheriting such a limited existence from his parents he opts for the only choice that appears to be a brighter future - he joins the Armed Forces. After all, if he makes it through boot camp then he will have a consistent paycheck and even an outside shot at leaving Earth by being assigned to the Navy. That has to be better than living in a PRC...