>>214541488
it dates back to medieval times, there are still churches with knights buried in the floor or in the walls
here's one that I found, seven martyred 13th century knights buried in a church wall, though you might notice it's in Portuguese not Latin because the earthquake of 1755 damaged the original tomb and they redid it

people often wanted to be buried in hollow ground, this usually meant their local church
the 19th century directly after the Napoleonic wars was a time of extreme instability with liberals and absolutists constantly fighting and a revolving door of governments, civil wars coups and counter-coups
progressives wanted to get rid of church burial for hygene reasons but out in the countryside there was a lot of resistance to this and the conservatives took full advantage of this resentement