The rally “round the flag” effect, first articulated by John Mueller in 1970, describes a surge in public support for a government or leader during international crises, often transcending pre-existing political divisions. This study systematizes the phenomenon by treating historical events like astronomical observations, quantifying measurable features to classify patterns. Using AI agent Grok, we identified and extracted data for 20 events spanning 1281 (Mongol Invasions of Japan) to 2022 (Russian Invasion of Ukraine), including triggering event type, public support surge, time to peak, duration, nationalist sentiment, opposition dynamics, external support, and ties to battle outcomes.