I know the date on his tombstone is 1844 but according to the Garrett Family Bible he was born in 1845. His sister Joann was born in 1844.

A Union Army Civil War veteran.
CO. B, 119th Illinois Infantry.
DEATH: A telegram received here last Saturday brought the sad news that Morg Garrett, of Brush, Colorado had passed away. He is the oldest brother of Tom Garrett, Mrs. Dan Baker and Mrs. Tom Lynch and would have been 72 years old in September. Mrs. Dan Baker and Tom Garrett took the train Sunday night for Brush, to attend the funeral on Monday. Interment took place at Brush. Franklin county Sentinel Aug 25, 1917.

BIOGRAPHY: Andrew Morgan Garrett-Regiment Name- 119th Illinois Infantry Side Union Company B. Soldier's Rank In Pvt Out Pvt Film # M539 roll 32 Union Illinois Volunteers.
the group was organized at Quincy, Ill., and mustered in October 7, 1862. Ordered to Columbus, KY., thence to Jackson, Tenn., and duty along Mobile & Ohio R. R. till December, 1862. Attached to District of Jackson, Tenn., 13th Army Corps (Old) Department of Tennessee, to December 1862. District of Columbus, KY.,16th Army Corps, to January, 1863. 3rd Brigade, District of Jackson, 16th Army Corps, to March 1863. 4th Brigade, 2nd Division, District of Memphis Tenn., 5th Division, 15th Army Corps, to January 1864. 1st Brigade, 2nd Division, Detachment Army of the Tennessee, Dept. of The Cumberland to February 1865. 1st Brigade, 2nd Division, 16th Army Corps Military Division West Mississippi, to August 1865.
SERVICE: Company G. captured at Rutherford Station and Company K at Dyer's Station December 21, 1862. Duty at Columbus, KY., and at Union City, Tenn., till Feb. 1863. Moved to Humboldt, Huntington and Memphis, Tenn., and guard railroad near Memphis till May 30. Moved to Memphis and Post duty there till January 1864. Ordered to Vicksburg, Miss., January 21, 1864. Meridian Campaign Feb 3 - Mar 2. Queen Hill Feb. 4. Meridian Feb 14-15. Red River Campaign March 10-May 22. Fort Debussy March 14. Occupation of Alexandria, LA., March 16. Battle of Pleasant Hill April 9, Natchitoches April 20-21. About Cloutiersville April 22-24. At Alexandria April 26 - May 13. Bayou Lamoure May 7. Retreat to Morganza, May 13-20. Mansura May 16, Yellow Bayou May 18. Moved to Vicksburg, Miss., Thence to Memphis, Tenn., May 21-Jun 10. Lake Chicot, Ark., June 6. Defeat of Marmaduke. Smith's Expedition to Tupelo, Miss., July 5-21. Camargo's Cross Road, near Harrisburg, July 13. Harrisburg Near Tupelo July 14-15. Old Town Creek July 15. Smith's Expedition to Oxford, Miss., Aug 1-30. Tallahatchie River Aug 7-9. Abbeville August 23. Mower's Expedition to Brownsville, Ark., Sept 2-10. March through Arkansas and Missouri in pursuit of Price Sept 17 - Nov 19. Moved to Nashville Tenn., Nov 21- Dec 1. Battle of Nashville Dec 15-16. Pursuit of Hood to the Tennessee River Dec 17-28. Moved to Eastport, Miss., and duty there till Feb. 1865. Movement to New Orleans, LA., Feb 8-26. To Dauphin Island March 6. Campaign against Mobile and its defenses March 17-April 12. Siege of Spanish Fort and Fort Blakely March 26-Apr 8. Assault and capture of Fort Blakely April 9. Occupation of Mobile April 12. March to Montgomery Apr 13-25. Return to Mobile and duty there till August. Mustered out August 26, 1865. Regiment lost during service 2 officers and 22 enlisted men killed and mortally wounded and 3 officers and 130 enlisted men by disease. total 157.