ΔE 10.8, fair: the same colour family, but not a straight swap. Tan Earth is noticeably lighter than Battle of Marathon.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Tan Earth is noticeably lighter than Battle of Marathon.
The same difference applies the other way round: Battle of Marathon is noticeably darker.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Battle of Marathon on the colour wheel See Tan Earth on the colour wheel
All matches: Battle of Marathon equivalents · Tan Earth equivalents