Using census-based data on the ability to recall one's age, we show that low levels of nutrition impaired numeracy in industrializing England, 1780 to 1850: cognitive ability declined among those born during the Napoleonic wars. The effect was stronger in areas where grain was expensive and relief for the poor, an early form of welfare support was limited. Nutritional shortages had a nonlinear effect on numeracy, with, severe shortages impairing numeracy more. Nutrition during childhood also mattered for labor market outcomes: individuals born in periods or counties with low numeracy typically worked in occupations with lower earnings.