This graphic by Charles Minard shows Napoleon’s army advance into Russia (thick brown band) and their retreat (thin black band). The width of the band represents the size of the army as it advances (left to right) and retreats (right to left). Temperatures are also shown.
Napoleon's army famously marched into Russia and was essentially destroyed. So the graphical map shows the size of the army marching in and out of Russia. Notice how the bands get thinner. That means the soldiers were dying. So the graphic tries to visually simplify this event.
The reproduction of this infographic is found in Edward Tufte's The Visual Display of Quantitative Information