Final answer:
Abraham Lincoln's suspension of the writ of habeas corpus during the Civil War exemplifies autocratic actions taken to preserve the Union and maintain national security.
Step-by-step explanation:
One specific action of President Abraham Lincoln during the Civil War that supports the view that he was one of the most autocratic presidents was his decision to suspend the privilege of the writ of habeas corpus. This extraordinary measure allowed for the arrest and detention of individuals without immediate cause shown, effectively suppressing dissent and ensuring that those considered disloyal to the Union cause could be held without trial.
Although this action was controversial, Lincoln justified it as a necessary step to maintain national security and preserve the Union during a time of rebellion and armed conflict.