Florida's role in the war has several facets we can address in brief:

1. Cattle. Florida was the largest cattle-producing state east of the Mississippi, so after the "Anaconda Plan" went into effect Florida was the main source of beef for the Confederacy.

2. Blockade running. Runners berthed at Charlotte Harbor, Tampa Bay, and elsewhere, and kept supplies incoming (mainly from Cuba) until the Union clamped down late in the war. Florida had the largest coastline in the nation at the time (No Alaska yet), difficult to patrol and full of little swampy inlets in which to hide. That's why the Confederate cabinet tried to flee here after Richmond fell, to hitch rides to Cuba and then on to England.

3. Salt and Natural Resources. Most of the fighting in Florida was made up of skirmishes and Union forays into the interior to destroy cotton warehouses, mills, salt works (along the coast), and to rip up tracks for the rail lines which funneled these resources northward.

4. Troops. The state contributed the largest amount of soldiers proportionate to its population of any state in the Confederacy. It didn't translate to as much in raw numbers, but Florida units were notorious fighters because... well, frankly they just didn't give a shit about summers farther north. Didn't matter how hot it was, it was pleasant compared to where they called home.

5. Military Experience. Perhaps the most important contribution Florida made to the Civil War occurred decades before it even began; a lot of credit is given to the US/Mexican War in cutting teeth for American generalship during the Civil War, but the 2nd (1835-1842) and 3rd (1855-1858) Seminole Wars warrant similar credit. Many of the men who would become most prominent on both sides of the war served in forts on the frontiers of Florida. Partial list here: http://www.pbchistoryonline.org/page/officers-served-in-seminole-wars-and-civil-war

I recommend any works on the subject by Joe Knetsch, Nick Wynne, and Robert Taylor for further reading.

Florida was an instrumental part of maintaining the blockade of the South during the war. Three of the few Southern fortifications to remain continuously in Union hands from the start of the war were located in Florida (Pensacola, Dry Tortugas, Key West) and they provided valuable service as hosts to blockading forces and thorns in the side of the Confederacy.

Indeed, George Pearce's Pensacola During the Civil War (2000, University Press of Florida) is subtitled "A Thorn in the Side of the Confederacy," partially because of the way it hosted Union soldiers. The battle for Fort Pickens outside Pensacola could easily have become (instead of Fort Sumter) the site of the war's first shots. Instead, Fort Pickens was an afterthought and never became directly critical to the conduct of the war.

There's a saying that "amateurs talk tactics (and Tiger tanks), while professionals talk logistics." I've changed the original somewhat, but the sentiment is the same. Forts Zachary Taylor (in Key West) and Jefferson (in the Dry Tortugas) were critical provisioning and supply depots for naval forces blockading the South. At the time of the war, Key West was the most populated and richest city in Florida, by virtue of its location on trade routes and the near-piracy of the salvors that made it home.

While Conchs exhibited a great deal of sympathy for the Confederacy, they were unable to muster the military support needed to oust Union soldiers, who maintained control of the city throughout the war. This ended up benefitting the town, which was the recipient of an enormous amount of military spending. This spending was somewhat tampered by extreme epidemics of yellow fever that swept through the town during the war years. Hundreds of soldiers ─ in particular black soldiers, whom the U.S. government deployed to Key West in the incorrect belief that they were somewhat less affected by the disease ─ died.

For much of the war, the Union operated around the periphery of Florida, with occasional battles as at St. John's Bluff, where a Union victory allowed the liberation of Jacksonville and gave the Union control of St. John's River and thus blocked easy Confederate transportation between Georgia and inland Florida.

There were raids by Union naval forces, particularly at Tampa, to destroy Confederate blockade-runners and commerce raiders.

In 1864, with the war swinging firmly in favor of the North, Union soldiers marched from Jacksonville (in Union control since October 1862) toward Tallahassee, aiming to capture the state capital. Unknown to the Union commander, the Confederates in Florida had been reinforced with regulars from farther north.

When the two forces met not that far west of Jacksonville, the Confederates won the resulting Battle of Olustee. It was a tremendously bloody battle, with more than a third of the Union force becoming casualties, one of the highest rates of the war. This was the only major direct combat action of the war in Florida, and it involved fewer than 10,000 soldiers all told.

Raids from Jacksonville and liberated portions of Louisiana, Mississippi and Alabama continued throughout the war. There was fighting at Gainesville and Marianna (in far northwest Florida), and at towns up and down the coast.

As the war continued to turn against the Confederacy, home guards and militia successfully defended Tallahassee against Union soldiers, giving that city the unique distinction of being the only Confederate state capital east of the Mississippi not occupied by the Union before the end of hostilities.

Beyond the battlefield, Florida figured large. Part of the reason for the capture of Jacksonville in late 1862 was the thought that north coastal Florida and portions of Georgia could be divided up into resettlement plots for freed slaves. This thought included Sherman's Special Field Order No. 15, which allowed the confiscation of 400,000 acres across the deep South, including Florida. This land was to be divided into parcels of up to 40 acres for distribution to freed slaves and their families. The order was ultimately revoked by President Johnson.