A letter written by Mark Twain announcing his engagement to Olivia Langdon in 1869 could make $20,000-30,000 at Early American History Auctions.

The lot is due to cross the block at the company's headquarters in California on February 14.

Mark Twain was one of America's greatest writers

Twain writes: My dear Mother & Brother & Sisters & Nephew & Niece, & Margaret: ---

"This is to inform you that on yesterday, the 4th of February, I was duly & solemnly & irrevocably engaged to be married to Miss Olivia L. Langdon, of Elmira, New York. Amen. She is the best girl in all the world, & the most sensible, & I am just as proud of her as I can be�Ǫ

"I am not worrying about whether you will love my future wife or not-if you know her twenty-four hours & then don't love her, you will accomplish what nobody else has ever succeeded in doing since she was born. She just naturally drops into everybody's affections that comes across her."

Twain met Charles Langdon, his future brother in law, while travelling in the Mediterranean in 1867.

Langdon introduced him to his sister and they hit it off almost immediately, although she would reject his first marriage proposal - something Twain references in his letter: "She said she never could or would love me-but she set herself the task of making a Christian of me. I said she would succeed, but that in the meantime she would unwittingly dig a matrimonial pit & end up tumbling into it-& lo! the prophecy is fulfilled."

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