In which year did the 5th and 6th Marines receive the French Fourragère for their actions during World War I?

The year in which the 5th and 6th Marines received the French Fourragère for their outstanding actions during World War I is indeed 1917. This distinction was awarded to recognize their exceptional bravery and performance in combat, particularly during key battles such as the Battle of Belleau Wood. The French Fourragère is a military honor bestowed by the French government, signifying the heroism displayed by those units during the war.

The selection of 1917 is significant as it was a pivotal year in the First World War, during which U.S. forces began to play a more substantial role. Honors such as the Fourragère help commemorate the sacrifices and valor of the Marine Corps in a critical period of history. The other years listed do not align with the timeline of events leading to the awarding of this honor, making 1917 the correct and notable year for this recognition.