During the period of the World War the Marine Corps personnel suffered casualties in actual battle in France with the American Expeditionary Forces (Second Division and Aviation); in Aviation while operating as part of the naval service in France; and in the West Indies in operations against the bandits of Santo Domingo.
Marine Corps deaths in the American Expeditionary Forces, as obtained from Marine Corps records on January 14, 1920, are divided as follows:
| Character. | Officers. | Enlisted men. |
Total. |
| Killed in action | 45 | 1,420 | 1,465 |
| Died of wounds received in action | 30 | 961 | 991 |
| Died of accident | 3 | 24 | 27 |
| Died of disease | 14 | 255 | 269 |
| Other causes | 1 | 11 | 12 |
| Total | 93 | 2,671 | 2,764 |
The following is a summary of the casualties sustained by the Fourth Brigade of Marines from March 15 to November 11, 1918, as published in General Orders, No. 66, Second Division, American Expeditionary Forces, dated July 2, 1919:
Fourth Brigade casualties.
(Part 1 of 2) Off. = Officers.
| Killed. | Died of wounds. |
Missing. | Wounded severely. |
|||||
| Off. | Men. | Off. | Men. | Off. | Men. | Off. | Men. | |
| Toulon sector (Verdun), Mar. 15–May 13 |
.. | 12 | 2 | 44 | .. | .. | .. | 16 |
| Aisne defensive and Chateau-Thierry sector, May 31–July 9, 1918 |
25 | 724 | 9 | 304 | .. | 33 | 3 | 322 |
| Aisne-Marne offensive, July 18–25, 1918 |
10 | 156 | 5 | 104 | .. | 66 | 9 | 250 |
| Marbache sector, Aug. 9–22 |
.. | 1 | .. | 1 | .. | .. | .. | 2 |
| St. Mihiel offensive, Sept. 12–Sept. 16 |
3 | 57 | .. | 86 | .. | 11 | 3 | 124 |
| Meuse-Argonne (Champagne), Oct. 1–Oct. 10 |
9 | 320 | 8 | 155 | .. | 31 | 23 | 380 |
| Meuse-Argonne offensive, Nov. 1–11 |
8 | 189 | 1 | 59 | .. | 20 | 7 | 222 |
| Total | 55 | 1,459 | 25 | 753 | .. | 161 | 45 | 1,316 |
(Part 2 of 2) Off. = Officers. undet’d. = undetermined.
| Wounded, slightly. |
Wounded, degree undet’d. |
Gassed. | Total. | |||||
| Off. | Men. | Off. | Men. | Off. | Men. | Off. | Men. | |
| Toulon sector (Verdun), Mar. 15–May 13 |
6 | 46 | .. | 89 | 4 | 287 | 12 | 494 |
| Aisne defensive and Chateau-Thierry sector, May 31–July 9, 1918 |
20 | 656 | 46 | 2,123 | 9 | 436 | 112 | 4,598 |
| Aisne-Marne offensive, July 18–25, 1918 |
20 | 489 | 30 | 911 | 2 | 39 | 76 | 2,015 |
| Marbache sector, Aug. 9–22 |
.. | 8 | .. | 3 | .. | .. | .. | 15 |
| St. Mihiel offensive, Sept. 12–Sept. 16 |
6 | 334 | 4 | 287 | .. | 4 | 16 | 903 |
| Meuse-Argonne (Champagne), Oct. 1–Oct. 10 |
43 | 862 | 6 | 480 | 6 | 141 | 95 | 2,369 |
| Meuse-Argonne offensive, Nov. 1–11 |
20 | 467 | 6 | 206 | 3 | 55 | 45 | 1,218 |
| Total | 115 | 2,862 | 92 | 4,099 | 24 | 962 | 356 | 11,612 |
The following table shows the casualties sustained by the Marine Aviation forces between April 6, 1917, and November 11, 1918:
| Character. | Officers. | Enlisted men. |
Total. |
| Killed in action | 2 | .. | 2 |
| Died of wounds received in action | 1 | .. | 1 |
| Died of accident | 6 | 6 | 12 |
| Died of disease | 1 | 25 | 26 |
| Died of other causes | 1 | .. | 1 |
| Wounded in action | 2 | 3 | 5 |
| Total | 13 | 34 | 47 |
From April 6, 1917, to September 10, 1919, 131 officers and 3,489 enlisted men died, a total of 3,620 Marine Corps deaths from all causes.
During the period between April 6, 1917, and November 11, 1918, one officer was wounded in action, four enlisted men were killed in action, and thirteen wounded in action, in the Dominican Republic in operations against bandits.
Two Marines died when the Cyclops was lost at sea.
Of the 60 naval medical officers, 12 naval dental officers, and 500 enlisted men of the Medical Corps of the Navy serving with the Marines in the American Expeditionary Force, 1 commissioned officer, and 12 enlisted men were killed; 8 commissioned officers and 101 enlisted men were wounded or gassed.