After defecting to Britain, Benedict Arnold led a British expedition into Virginia late in 1780. He raided Richmond and reached Portsmouth on January 19, 1781, establishing headquarters in Patrick Robinson's house. His troops used local buildings as barracks and prisons and fortified a base from which they threatened the James River and Virginia's interior.

This position formed part of a wider contest of maneuver rather than an isolated event. Commanders selected camps and routes to protect communications, obtain forage, watch an opponent, and preserve options for retreat or attack. Armies dispersed to gather supplies and concentrated when danger approached. Scouts, cavalry patrols, and local informants tried to reduce the uncertainty created by poor maps and delayed messages. Civilians faced requisitions and the risk of violence whenever opposing columns crossed the same district. Reading the marker in this larger setting shows how movement and positioning shaped the campaign before its best-known battle or surrender.

The surviving marker text adds further detail: Arnold, after going over to the British, was sent to Virginia to make war on the state. He reached Hampton Roads in December, 1780, raided to Richmond and came to Portsmouth, January 19, 1781. Establishing his headquarters in Patrick Robinson's house, and using the old sugar house on Crawford Street as a prison and barracks, Arnold remained here until spring. Then again he went up the James to open the fateful campaign of 1781 that won the war for America.

The site's significance is clearest when interpreted at several scales. Locally, it shows how residents and landscapes were drawn into wartime demands. Regionally, it belonged to routes of communication, supply, government, or military movement. Nationally, it demonstrates that independence emerged from thousands of connected decisions and actions rather than from famous battles alone. The physical location anchors those relationships and helps explain why timing, distance, terrain, and community participation mattered to the outcome.

The marker at Benedict Arnold at Portsmouth Marker makes this history legible in a modern landscape that has changed substantially since the eighteenth century. Its value lies in identifying the approximate place and connecting it to documented people, movements, and institutions. Visitors should distinguish the historic event from the later act of commemoration: the marker is evidence of how the episode has been remembered, while its text and setting guide interpretation of the original event. Considered with contemporary records and the broader campaign, the location adds geographic meaning to a story that might otherwise survive only as names and dates.