Letters to the Editor: are they examples of Free Speech?

I started writing letters to the editor in Montgomery, Alabama during the late 1950's. One needn't have been a genius to understand that a degree of subtlety was required when writing anything which could have possibly been construed as an attack on segregation.

For the most part, my letters met this test, and escaped the attention of those in the city prone to violence. But one particular letter evidently went too far, and I started receiving late night phone calls. The messages ranged from heavy breathing to demands that I get out of town. My employer at the time, Western Electric, was encouraged to fire me. They refused.
In addition to being frightened, I was infuriated. Here was proof that, in a supposedly free country, I was unable to speak my mind without being threatened. I continued to write letters, albeit with what should have been an unnecessary amount of discretion .
After I left Montgomery, some months later, I received a letter which remains one of my prized possessions. It was from Ray Jenkins, managing editor of the Alabama Journal. He commented on a letter I had written and which appeared in the Journal. The subject of the letter was a weekly columnist who was, I felt, intellectually bankrupt.

My letter: Gandhi and Hitler
I wish to comment on the "As I see it" column in last Sunday's Journal. I was surprised, for example, to discover that Mahatma Gandhi was Hitler's right-hand man. It's really amazing how one can re-learn history with the help of an expert like Mr. Mahoney. He points out seemingly insignificant facts which, though a little circumstantial , culminate in a smashing indictment. For example, given the fact that Gandhi and Hitler were both vegetarians, the conclusion that they were fellow conspirators is inescapable.
Little gems of irrefutable logic such as this make my Sunday mornings complete.

Mr Jenkins letter:
Dear Mr. Siltman,
I keep handy in my desk an old yellow clipping headlined, "Ghandi and Hitler." Every time I get despondent, all I have to do is read it and get a lift.
Seriously, if a reader ever knocked me out as effectively as you did my colleague, I'd never write another column.
Ray Jenkins
Managing Editor
Alabama Journal