I just added this 1813 Military Guinea to my collection. It is in an NGC AU-58 holder. I have had a hard time getting a good picture of the obverse. I have been researching the mintage of this piece. Many dealers claim that 80,000 were struck. The British Mint says the number was 360,000. Maurice Bull is more precise at 361,473, His number is based upon the amount of gold the Royal Mint reported that they handled divided by the weight for each gold guinea. Obviously that is quite a disagreement. These coins were made for Wellington’s army during his 1813 Pyrenees campaign. It is often said they were used to pay the soldiers. It was also said the local people would not accept the Spanish Milled Dollars the British had in large numbers. They would only accept gold. Therefore these guineas, which was the first coinage of the denomination since 1799, were struck for that purpose. It is a one year type coin, and since they were used for military purposes, they are called "military guineas." They were not made to circulate in England, and it is claimed that only a limited number were used there. In 1817, the British introduced their reform coinage. The guinea, which was worth 21 shillings was replaced by the sovereign which had a value of 20 shillings. The sovereign has retained the same weight down to the present day. Here is an example of the first year of the sovereign, dated 1817.
The British also issued a half guinea in 1813. Some dealers advertise it as a "Military Half Guinea." While the British undoubtedly used the coin for military purposes given the role the guinea, it's a bit of a misnomer. Unlike the 1813 guinea, the 1813 half guinea is not a one year type coin. Furthermore it was not a unique issue, like the guinea, because the British continued to issue it on a regular basis after the coinage of guinea was suspended in 1799. Here is an 1806 half guinea.