Does dutchman have a capital d in the middle of sentence?

No, "Dutchman" does not have a capital "D" in the middle of a sentence.

The only time "Dutchman" is capitalized is when it is used as the first word of a sentence or when it is part of a proper noun (like a person's name).

For example:

* Correct: "The Dutchman walked down the street."

* Correct: "John Smith, a Dutchman, arrived in New York."

* Incorrect: "He was a Dutchman."