What happened to them?

During the period of service for the Third Michigan Infantry, of 1,411 total enrolled, and based on data up to June 10, 1864 when the regiment was consolidated with the Fifth Michigan:

2 officers were cashiered
1 was branded and drummed out of the regiment
54 men deserted
1 died accidentally
80 died of disease
47 died of wounds
103 were killed in action
450 were discharged for disability
128 were mustered out
7 never joined the regiment
3 were sent to prison
39 officers resigned
28 men simply disappeared (listed as “no further record”)
1 was “killed”
1 man was murdered

At least 457 men were transferred: 46 to the Veteran's Reserve Corps (the "Invalid Corps"), 31 to regular army or navy units, 362 to the Fifth Michigan Infantry and 18 to other state regiments. (photo: Allen Shattuck; source: Michigan at Gettysburg.)

Between late December of 1863 and March of 1864 206 men reenlisted as “veteran volunteers”. The company with the highest number of reenlistments was G company with 24 reenlistees (or 13.4% of the total reenlisted) and the lowest was B company with 11 (6.1%); the company average was 18. Of that number 191 men were transferred to the Fifth Michigan in June of 1864:

41 to A company
44 to E company
54 to F company
51 to I company
1 to Staff

(At least 15 men died prior to consolidation of the Third with the Fifth on June 10.)

Inclusive of dischargees, transferees, and men mustered out who reentered the service, 363 men would reenter the military and serve in a second unit, and of those who reentered the military 58 men would serve in a third unit.

At one time or another during the war a total of 84 men served in the Invalid Corps (the “Veterans Reserve Corps”), and 6 of those would join a third unit.

Next: How many died?