The New York Times is running a series of articles/essays/whatchemacallits ("blog", perhaps?) dealing with the ACW and various aspects of it. To quote its own blurb:
One-hundred-and-fifty years ago, Americans went to war with themselves. Disunion revisits and reconsiders America's most perilous period -- using contemporary accounts, diaries, images and historical assessments to follow the Civil War as it unfolded.
New articles are posted fiveish times a week, and each is long enough to delve a bit into detail, but not so long as to make a prolonged read that you need to plan for in advance
The topics are varied, but usually deal with "something" that happened 150 years ago, i.e. this summer has seen articles that are tied into events of the summer of 1861 in some way.