He did serve at West Point as a Colonel -- your key item, that he skipped LTG, is correct; I was not clear earlier. He was a BG for a very short time. Later got moved from MG directly to to GEN over 20 plus people and appointed Vice Chief, a job he held for only five or six months IIRC -- then back to the WH...
Annoyed the Army no end.
One of many reasons why Nixon is second only to Johnson as the worst President of the last 100 years or so...