Here is the "long story" of the Medieval II 1.5 update. When Medieval II: Total War launched in late 2006, it was a critical success, but the technical reality was shaky. Following the release of the Kingdoms expansion in 2007, the community became fractured. There were separate executables for the base game and the expansion, and a slew of bugs plagued the new campaign mechanics (like the Americas campaign and the Britannia campaign). Defyingchase2018720pwebdlhindichinesex2 Updated
However, there is a modern twist to this story: Srkwikipad: Link
Because the game was released in 2006, the term "15 patch" is almost universally a typo for . This patch is legendary among the fanbase because it didn't just fix bugs; it fundamentally changed the game into the stable platform used by modders for nearly two decades.