Short answers, pulled from the story.
The Capture of New Orleans took place from the 25th of April to the 1st of May 1862, during the American Civil War. Flag Officer David G. Farragut fought past Forts Jackson and St. Philip on the 24th of April, and Union forces under Maj. Gen. Benjamin Butler occupied the city on the 1st of May.
Flag Officer Farragut bombarded Fort Jackson and Fort St. Philip from the 18th to the 28th of April 1862 in the Battle of Forts Jackson and St. Philip, then fought his fleet through the Confederate defenses. He managed to get thirteen of his ships upriver on the 24th of April. Historian Allan Nevins noted that Confederate defenses were weakened by disorganization, poverty, lack of skilled engineers, and friction between state authorities and Richmond.
Confederate generals had planned for an attack from the north, not from the Gulf of Mexico. The Union approach upriver from the Gulf came as a surprise. Major General Mansfield Lovell, commanding Confederate Department 1 in Louisiana, was left with evacuation as his only viable option after Farragut's fleet broke through the river defenses.
Butler's General Order No. 28, issued on the 15th of May 1862, ordered that any woman who insulted or showed contempt for a Union officer or soldier in New Orleans would be treated as a prostitute. The British House of Lords called it "one of the grossest, most brutal, and most unmanly insults to every woman in New Orleans." Butler was removed from command of the Department of the Gulf on the 17th of December 1862, and many attributed his removal to the order's international fallout.
New Orleans had an estimated population of 168,675 at the time of the Civil War, making it the largest city in the Confederacy and larger than the four next-largest Southern cities combined. By 1860, trade worth 500 million dollars passed through the port annually, with 33 different steamship lines operating there.
The occupation accelerated the collapse of Confederate slave labor across the region. Butler's contraband of war policy, which he had established earlier at Fort Monroe, meant Union forces accepted enslaved people who fled Confederate control. The Confederacy responded by pulling enslaved workers away from areas near Union lines, depriving Confederate armies of a labor force they had counted on. At Jefferson Davis's plantations at Davis Bend, Mississippi, enslaved workers revolted in May 1862, seized the property, and armed themselves to resist Confederate recapture.