This achievement is the "negative" ending of the Canid's Cradle quest, given to you after finishing your business with the Broker on Monarch. This results in a war between the Iconoclasts and the MSI, the player required to choose a side.
I recommend checking if your actions up to this point allow you to broker peace between the factions, as war is the default.
Your playthrough will either allow you to complete "Peace In Our Time", or "Monarch Abides". Although they are mutually exclusive, a good manual save can allow you to get both of these achievements in one run.