Chains Of Command by Marko Kloos

In the aftermath of devastating defeats and growing political infighting, a battle-hardened officer is pulled into a sensitive assignment that exposes corruption and self-serving agendas at the highest levels while an implacable alien threat looms. Torn between obedience and conscience, he defies reckless orders to protect abandoned troops and civilians, assembling a small team to deliver aid and evidence even as the front collapses. The result is a taut blend of battlefield action and political intrigue about loyalty, accountability, and doing the right thing when the system won’t.

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