In the 1870s there were few serious competitors aside from Wanderers and the Royal Engineers for the title of the best club in England. It was fitting that these 2 sides contested the first FA Cup Final, and there was a period from 1871 -1875 when the Royal Engineers won just about every game that they played other than FA Cup Finals. Wanderers of course won the FA Cup 5 times in 7 seasons.
In the previous decade matches between the 2 had been far more casual in nature.
Here's an account of an early meeting in which the military metaphors are done to death, Note that the mention of the after match hospitality was almost obligatory in football journalism during the 18th century. Its a curious team list as well...
Kentish Chronicle-19.11.64
Four years later the Wanderers don't come across as one of the leading clubs, managing to muster only 8 players for a home fixture and failing to ensure that there was a football available! The thoughts of the Engineers on travelling up from Chatham for a 35 minute game are unrecorded. As Charles Alcock may (or may not) have said, its a funny old game...
Bell’s Life in London and Sporting Chronicle - 05.12.68