Credit to previous suggestions

England 375:

Having imprisoned the ineffectual Henry in March 1461, Edward and his supporters faced a formidable army raised by Margaret and the Lancastrians at the Battle of Towton, a small Yorkshire village, on 29th March 1461.

Item 1:

https://backpack.tf/item/16404856122

Sale 1:

https://backpack.tf/profiles/76561198145296318#!/compare/1760918400/1761004800

https://backpack.tf/profiles/76561198359390706#!/compare/1760918400/1761004800

bulk

Sale 2:

https://backpack.tf/profiles/76561198359390706#!/compare/1762387200/1762473600

https://backpack.tf/profiles/76561198050414618#!/compare/1762214400/1762473600

sold for hat without a home (priced at 17)

17

Sale 3:

https://backpack.tf/profiles/76561198050414618#!/compare/1762732800/1762905600

https://backpack.tf/profiles/76561198201862513#!/compare/1762905600/1762992000

sold for big kill

Big Kill:

https://imgur.com/a/yaYeTMC - snapshots

https://imgur.com/a/K2WcATP - common sellers past 7 days

rounds to 13 keys

Sale 4:

https://backpack.tf/profiles/76561198201862513#!/compare/1762992000/1763337600

https://backpack.tf/profiles/76561197964195441#!/compare/1762992000/1763078400

untrace

13-17