During this week 150 years ago in the war, U.S. Navy Flag Officer David Farragut takes his Union fleet and runs it past two heavily armed Confederate forts on the lower Mississippi River near the Gulf of Mexico. The daring move leads Farragut onward to capture New Orleans on April 25, 1862, forcing a sullen Southern city to surrender.

It’s one of the most eventful months of the war yet. And Farragut’s daring provides the Union a key victory in its thrust to seize the main inland waterway and divide the Confederacy. New Orleans is one of the busiest Southern ports and a supply lifeline for the secessionist states.

Farragut’s plan involved weeks of sizing up Confederate-held Fort Jackson and Fort St. Philip several miles downriver from New Orleans. His forces spend days pounding the forts with intense fire from mortar boats while crews cut a gap in heavy chains strung across the river.

Then, hours before dawn on April 24, 1862, Farragut’s fleet begins moving stealthily upriver, racing a gauntlet of raking fire from the forts. The fight is intense, and The Associated Press reports in an April 24 dispatch that there was a “heavy and continuous bombardment of Fort Jackson” before Farragut’s move.

The Confederates reported to AP that Fort Jackson alone had been targeted by some 25,000 13- inch shells, but they vowed the fort was capable of absorbing heavy fire indefinitely. Farragut chose instead to bypass the forts entirely.

All told, 13 of Farragut’s ships would make it upriver beyond the two forts and continue on to New Orleans to force its surrender.

There are more than 1,000 casualties on both sides. And Confederates still holding the forts downriver surrender on April 28, 1862, when they realize their garrisons are cut off and isolated.