Here is his 1838 obituary. I believe his list of battles is possibly correct since he served in the Maryland First of the Continental Army. This is the only indication I have located that suggests he had been wounded, but it is probably true.
[From the Cumberland Civilian, January 12th. 1838]
Died on the 8th inst. Col. William Lamar, in the 83rd year of his age. Colonel Lamar was a native of Frederick County, and had been a resident amount us for more than thirty years. He entered the revolutionary army shortly after the Declaration of independence, in the 21st year of his age. He was appointed an ensign at the age of 21, and not long afterwards was promoted to the rank of lieutenant, then made quarter-master and finally promoted to the rank of Captain of the Seventh Maryland regiment. The captain was engaged in active service from the beginning to the close of the war, and never returned to his home but once during the whole time, and he enjoyed but a short respite from duty. He was engaged in every important battle, fought in the east until 1780; at Harlem Heights, White Plains, Germantown, Monmouth, Staten island and other places. In 1780 he marched to the South, and at the battle of Camden was fighting by the side of De Kalb, under whose immediate command he was when that lamented officer was killed. With the Southern army Col. Lamar remained an active officer and soldier until the close of the war; was at the battle of Guilford Court House, at Eutaw, and assisted at the capture of Forts Mott, Granby and Watson. The desperate charge of the American troops, which turned the scale of battle in their favor, was ordered by Gen. Greene, at the instance of Col. Lamas, whose suggestion was communicated to the General through major Anderson. At Fort Mot the Colonel also distinguished himself by suggesting setting fire to the fort, which was successful, and in a few moments compelled the garrison to surrender. The Colonel was also engaged at the siege of Ninety-six under Gen. Greene. He had command of the mining party, a brother officer of Virginia was associated with him, but was compelled to withdraw on account of sickness. It was here the Colonel (editor’s note, this rank refers to Lamar who had probably gained the nickname colonel later in life) met Kosciusko, the immortal Polander, of whom he used to take great pleasure in relating the following anecdote. The Colonel being left in sole command of the mining party was anxious to procure some subaltern officer to assist him. Kosciusko hearing this, immediately came forward and magnanimously offered to serve the Colonel in the capacity of subaltern, and agreed to remain with him constantly. The colonel used to say he preferred Kosciusko to any other officer in the army. The Colonel received several wounds in the battles of the Revolution, was shot in the thigh at Guilford and in the breast at Eutaw. Notwithstanding the many sufferings and privation he had to endure in the army, I have heard him say that his "term of service was the most happy and joyous period of his life; that he became fond of the changing success of military life and was never disturbed by the least sense of its dangers." The Colonel married early and had several children whom he had the pleasure of seeing raised to the head of prosperous families. As a husband and father, he was exemplary. By his industry and enterprise he acquired a valuable estate which he divided amount his children as they respectively arrived at age and married. He retained for himself no more than was sufficient together with his pension to support him. As a citizen, above all as a companion, the loss of the Colonel will long be regretted. Always cheerful he was a most welcome visitor whenever he came. There was no countenance that would not brighten with a smile at the approach of the colonel. In him old age had put on the greenness and vivacity of youth. He delighted to the last in all the pleasantries of boyhood and retained most of his susceptibilities. In the several last years of his life he almost lived on horseback, and no boy, however much accustomed to such exercise was a better jockey than the colonel. He has been known within the past year to ride upwards of sixty miles in one day. He has proposed to ride any distance not exceeding one hundred miles in one day, provided he could be furnished with suitable horses, and would bet that he could ride a fast any other man, either in a single day, or for any number of days, continuously. Col. Lamar died as the exhausted taper dieth. He fell as the fruit falleth in autumn at the full period of ripeness. Death with him was but the falling off to sleep the system had gradually worn out, and the breath of life seems to have left him unconsciously. Death for once turned counterfeitor and put on the likeness of tranquil sleep, for as if he had fallen away into a sweet repose so did my lamented and venerable friend appear hushed in death. May his cheerful and happy spirit be in the enjoyment of more perfect bliss, and may death to him have been only he medium for an exchange of feeble old age into a life of perpetual health, beauty and happiness.