ΔE 10.1, fair: the same colour family, but not a straight swap. Mournfang Brown is cooler than WWI German Red Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Mournfang Brown is cooler than WWI German Red Brown.
The same difference applies the other way round: WWI German Red Brown is warmer.
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 WWI German Red Brown on the colour wheel See Mournfang Brown on the colour wheel
All matches: WWI German Red Brown equivalents · Mournfang Brown equivalents