This interactive D3.js v7 visualization recreates Minard’s 1869 flow map of Napoleon’s 1812 Russian campaign, showing the army’s shrinking size through tan (advance) and black (retreat) bands whose width encodes troop numbers. It plots city markers with dates, river crossings, and a temperature chart, displaying tooltips on mouseover. The code uses `d3.csvParse` to load troop, city, and temperature data, then renders the map with SVG paths via `d3.area` and `d3.curveLinear`, while implementing custom mouseover handlers for the annotations.