Let's take a nice, small, tactical Joint action going in to the New Year.
You're outnumbered six to two. Your enemy's ships are better armed, manned, and provisioned. They guard one of your cities that they have held for a year and they have many soldiers ashore.
Your army, navy, and nation are strangled by a blockade. You need that city. You need that port.
What do you do? Attack - of course.
For a naval attack he placed artillery and dismounted cavalry from Sibley's brigade, led by Colonel Thomas Green, aboard two river steamers, the Bayou City and the Neptune, commanded by Capt. Leon Smith. Magruder gathered infantry and cavalry, led by Brig. General William R. Scurry, and supported by twenty light and heavy cannons, to cross the railroad bridge onto the island to capture the federal forces ashore. To meet the attack Renshaw had six ships that mounted twenty-nine pieces of heavy artillery.The Northern invaders actually were hit even worse - they had over 400 soldiers taken prisoner.
The Confederates entered Galveston on New Year's night, January 1, 1863, and opened fire before dawn. Cook failed to seize the wharf because of the short ladders provided for his men. Naval guns helped drive back the assault. Then the Confederate "cottonclads" struck from the rear of the Union squadron. The Harriet Lane sank the Neptune when it tried to ram the Union ship, but men from the Bayou City boarded and seized the federal vessel despite the explosion of their own heavy cannon. Renshaw's flagship, the Westfield, ran aground, and the commander died trying to blow up his ship rather than surrender it. The other Union ships sailed out to sea, ignoring Confederate surrender demands, which could be enforced only upon the abandoned federal infantry in town.
Magruder had retaken Galveston with a loss of twenty-six killed and 117 wounded. Union losses included the captured infantry and the Harriet Lane, about 150 casualties on the naval ships, as well as the destruction of the Westfield. The port remained under Confederate control for the rest of the war.
Why did they lose? Simple - poor leadership and a lack of battlemindedness. The occupation made them complacent and over-confident. All the equipment in the world will not help you if you don't have the right leadership.