Here we are at a data center outside of Chicago, Illinois.

There are facilities like this all over the United States.

And every day, millions of websites, e-mails, tweets, and cat photos are stored inside of them.

SPEAKER 1: Recently though, we've learned that our information might not be as secure as we thought.

People like Edward Snowden have come forward and revealed that the US government had been spying on its own citizens through organizations like the NSA and CIA.

By tapping into this digital information, our government could access our emails, listen in on our phone calls, and even track our location via GPS.

Now, while this high-tech surveillance may seem like something that can only occur in modern times, we can actually see the traces of it all the way back during the Civil War.

That's right.

Abraham Lincoln had access to the entire country's cat photos.

I don't think that sounds right at all.

It's true.

They used to call him "Meowbraham Lincoln."

SPEAKER 2: Using spies and surveillance techniques during times of war is nothing new.

SPEAKER 1: It helps to know your enemies' numbers, where they're moving, and what their attack formations might be.

SPEAKER 2: And there were plenty of spies on both sides of the war to help their generals with this valuable information.

SPEAKER 1: The Union Army even had a hot air balloon brigade to help track the movements of Confederate troops.

SPEAKER 2: Yet the Civil War was a different kind of conflict.

It pitted countryman against countryman.

Families were torn apart.

SPEAKER 1: It was a battle on our own turf against our own people.

Neighbors in the same community couldn't be sure they were on the same side.

We were fighting a new kind of war and we needed a totally new form of espionage.

The scope of espionage surprised me.

Just about every Army command had its own spy operation.

And they were looking at people in their communities.

SPEAKER 2: This is Stephen Towne, archivist and author of-- "Surveillance and Spies in the Civil War."

And it's got a colon and something after that.

I can never remember what the rest of it is.

SPEAKER 2: Don't worry, Stephen.

We got this.

"Surveillance and Spies in the Civil War-- Exposing Confederate Conspiracies in America's Heartland."

He basically blew the whistle on surveillance during the Civil War.

Yeah, he's like Edward Snowden, if Edward Snowden waited 150 years to blow the whistle.

It is very possible that this could be the first instance of at least the US Army spying on its people.

There were spies in lots of wars before this one.

This isn't even the first American war to utilize espionage.

George Washington had spies in the American Revolution.

But what was unique about the Civil War wasn't that the North and South armies were spying on each other.

It was that the government was spying on its own citizens.

Because there was a lot of what was perceived to be disloyalty in the North.

Many people in the North were not in favor of the Union government, coercing the Confederates back into the Union.

A lot of them just didn't want to go to war.

Some even sympathized with the Confederates and thought that the states had a right to secede, or that the federal government was asserting too much authority.

SPEAKER 2: Many union farmers were against the war, because they sold a lot of their produce to the South.

There were also plenty of Northerners who left to join the Confederate army, and some even formed resistance groups within the Union.

SPEAKER 2: This was something that Union generals were especially worried about.

They needed a way to keep track of what was going on in their territory.

STEPHEN TOWNE: And so they would hire local people to be hired detectives.

Or they would detail some of their soldiers to put on civilian clothes and go out into different communities and to nose around.

Back then, there weren't any state police forces, and the FBI didn't exist.

So the Union had to work with what they had.

But hiring enough detectives to go door to door in every town to investigate every possible instance of insurrection was too expensive for even the Union.

Thankfully, there are plenty of people ready and willing to spy on their own neighbors.

STEPHEN TOWNE: Initially, this really starts out with people writing their governor or other people saying, my neighbor is disloyal.

Or there's a bunch of disloyal people who are talking treason and they're saying that they're not going to fight for the Union cause and that they are sympathetic to the Confederates.

They're rebels.

The governors did not have investigatory staff.

They didn't have police forces at their command.

Or a team of James Bonds.

Right, they didn't.

So they relied on trusted people in various communities around their states to do this.

So the Union Army generals cultivated a network of citizen spies to keep an eye on their neighbors and report any suspicious behavior.

So the government basically got people to tattle on each other.

But they wanted to take it a step further.

So they got the cooperation from postmasters in different cities and towns and said, hey, we want to look at so-and-so's mail.

And so the Army was going through people's private mail and finding information that way.

Hmm, going through people's private mail.

That sounds familiar.

Yep.

And just like our modern NSA, the Union Army was also monitoring people's text messages, or rather the Civil War equivalent of text messages.

Telegraphy was very important in this.

And telegraph offices were ordered to hand over to the federal government messages that might implicate people who had Confederate sympathies.

And so all these things were collected and brought into Washington, where they were sifted by what were described as judicious men who would look through these things to look for disloyalty and treason in the North.

Glad we don't live in a world that remotely resembles that one.

But government snooping wasn't the only thing to get its start during the Civil War.

Some of the first hacking was done then too.

But since computers wouldn't be around for, like, another 100 years, these civil war hackers had to settle for the state of the art technology of the time-- telegrams.

Telegraphs.

Have you ever heard of a guy named Lightning Ellsworth-- George "Lightning" Ellsworth?

He was a telegraph operator who worked for Confederate general, the famous raider John Hunt Morgan.

And in 1862, he went with Morgan as his telegraph operator.

But he would tap into the lines, find out where the Union forces were, so that Morgan's raiders, his troops, would avoid them.

But also he would send messages that would send Union troops in the wrong direction or trap them.

So that was an innovative thing.

It got a lot of press at the time in 1862 and 1863.

And Ellsworth because a minor celebrity.

The early days of wiretapping.

Exactly, exactly.

Many people started mimicking George "Lightning" Ellsworth.

And so Union operators and other Confederate operators were constantly, by the end of the war, tapping into each other's lines and mimicking different operators' styles so they could send out misleading information and that kind of thing.

While many of these tactics were used to sow confusion among the enemy and win the war, oftentimes the government would use its intelligence networks to silence dissidents, make arbitrary arrests, and even convict people of treason.

And many people spoke out against what they saw as the government abusing its powers, only to be targeted themselves by this surveillance.

And sometimes this surveillance led people to be convicted of treason.

It wasn't until after the war that some of these people were allowed to go free.

One example of this was a US Supreme Court case in 1871, where it was ruled that a military tribunal held during the war was unconstitutional.

Three men were exonerated who were previously convicted of treason.

The man responsible for their capture was Brigadier General Henry B. Carrington, head of the intelligence network in Indiana.

SPEAKER 1: During that trial, his testimony revealed the full scope of his spy network.

He said on the stand that there were thousands of people who supplied him with information.

So he's talking about not just the special agents and the detectives and the soldiers who were detailed as spies.

But he's talking about the telegraph operators, the clerks in the stores who were supplying information on gun sales, the railroad conductors who were telling about who's traveling on the railroads, and then the letters that are coming in from people in the communities.

So it all adds up to a large number of people.

SPEAKER 2: Today, the Union is one and we are not currently engaged in a bloody conflict with our own people.

Yet we still find ourselves in a situation similar to what was going on during the Civil War.

The knowledge that we might be spied on by the government is so commonplace that we often joke about the NSA reading our emails or listening to our phone conversations or our name will be put on a list somewhere if we say something bad about the government, like, you're not my favorite government.

Ehh.

I shouldn't have said that.

While the idea of being spied on might anger us and it might seem to go against the very principles our country was founded on, whenever we make a phone call or check our emails, there is a part of us that expects someone to be listening in on the other side.

Can we edit out that last shot where I said something bad?

Yeah, we'll do that.

So what do you think?

Is government surveillance on its citizens a necessary part of keeping our country safe?

Or maybe it should be limited to reading only our telegraphs.

Let us know in the comments.

The government might read the comments.

This episode is brought to you by PBS Learning Media, a great source for classroom resources on Civil War history.

If you're interested in finding more videos or lesson plans on what we talked about today, check out our page on learning media here.

And for a more dramatic take on the Civil War, you should check out the new series "Mersey Street" on PBS.

A lot of what we explored in this episode gets talked about on that show too.

So head to PBS.org to find more.