Here's a few things off the top of my head, mostly Marine uniform history:
Medals have been worn over the left breast to cover the heart and therefore give it a little more protection. (Duh)
Marine officers wear a 'quatrefoil' (gold rope-like design with four loops) on top of their covers (hats). Back in the day Marines acted as snipers in ship's rigging, picking off the bad guys. Marine officers started putting that particular knotted rope on their covers to differentiate themselves from the enemy.
Marine NCOs and above wear a red strip down the legs of their dress trousers, called a blood stripe. This is in memory of the battle of Chapultepec (had to look up the spelling) where 90% of the casualties were NCOs.
Marine officer's dress swords are known as Mameluke swords. They are copies of the sword given to the Marine commanding officer when the Marines went to Tripoli to try to reinstate the rightful ruler. I believe this piece of equipment is the oldest one in use by the armed forces.
Marines of the 5th and 6th Marine Regiments wear a green and red (mostly green) braided rope-thing on their shoulders. It is a French Fourragère (again, had to look up the spelling) and it was awarded to those units during World War I. An Army unit was also awarded the Fourragère in green and red, but theirs was mostly red. I
think this is for the unit's heroic actions during the battle for Bellow Wood (sp), which afterward was renamed The Marine's Wood. The history of the Fourragère
I HEARD was that some French unit turned and ran from a battle. Some of them were subsequently caught and hanged. The commander then had each soldier make a noose and wear it on their shoulder as a reminder of what would happen if they ran away. The soldiers then fought so well that afterwards their nooses were worn as badges of honor. But that's just a story I heard.
Marines have seven belt loops, to represent the seven seas. (But that could just be a made up reason for why trousers have seven belt loops

)
The Marine's wear an EGA, or Eagle, Globe, and Anchor. The Eagle represents the United States. The Globe (showing the Western Hemisphere) represents the worldwide service of the Marine Corps. (I think the British Marine's Globe shows the Eastern Hemisphere) The anchor acknowledges the naval tradition of the Corps. The anchor has a rope (line) wrapped around it, known as 'fouled'. (Not sure why that is) Or you could just say that the EGA represents the Marine's service on air and land and sea: Eagle, Globe, and Anchor. There are some slight differences between the officer's and enlisted's EGAs. Notably, Cuba is not on the officer's EGA because no Marine officers were present during that campaign. Freakin' officers.
Not sure of the specifics here, but everything is essentially correct. I'm sure you can Wiki the details.
(End history lesson)
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