Because if they waited until the warships got there, they would be facing simultaneous cannon fire from the warships and fort Sumter at the same time.
What Military officer would be so stupid as to put himself in the position of being attacked on two fronts simultaneously?
Considering the size of the Confederate artillery at Charleston the likelihood is that the Union task force would have been mauled at the least and possibly destroyed or captured
That is exactly correct. Admiral Porter, in his memoirs, said that every ship would have been sunk. Other military people at the time believed it would end in disaster.
I think any objective person can look at the arrays of forces on both sides and realize the mission as was written in it's orders, a suicidal mission.
Had those ships done as their orders indicated they would do, they would have been destroyed. Those ships did not do as they were expected because mysteriously, their command ship the "Powhatan", never arrived to take charge of their forces. By this "miracle" of "miscommunication", those ships that would have been destroyed, were prevented from being destroyed.
Abraham Lincoln was just astonishingly lucky that there was a "miscommunication", and somehow the command ship had been detached from the mission and sent to Pensacola by his secret orders, and this "lucky" event prevented the destruction of those ships in Charleston harbor.
Boy, that Lincoln sure was "lucky" in making that mistake. Had he not accidentally sent those countermanding orders for the Powhatan, those warships would have attacked the confederates and their massed cannon emplacements, and they would have been destroyed.
Did Lincoln realize the likelihood of all those ships being destroyed prior to sending them? Anderson had sent diagrams of the confederate gun emplacements and staffing in his dispatches to Washington, and so the military officials there could have advised the President how very likely was the destruction of those ships if they followed the orders they had been given.
Lincoln must have been exceptionally cruel to have sent those men to their certain deaths, and it was only by the wildest stroke of luck in sending those secret orders to detach the command ship was the expedition prevented from being destroyed.
They should call him "lucky Abe."
How is it such a brilliant man made such a lucky mistake on so serious of an issue as the resupply/reinforcement of Fort Sumter?
This would have been a clear demonstration of the CSA acting only to defend its sovereignty. So why attack Sumter and its puny garrison those losing the PR advantage?
Their spies had informed them those ships were coming, but when Lincoln called for ships to be sent, he was sent a much bigger list than what was actually sent. The confederates had no actual idea of what war assets were really coming, and they could only conclude that whatever was being sent, it would be deemed sufficient to accomplish the task for which it had been sent.
The thought that Lincoln would send a force that they might have easily destroyed had likely not occurred to any of them. They believed the force to be formidable, or why else would it be sent?
Confederate communications illustrate the preparations they made to deal with this coming force, and according to their message traffic, they really believed they were about to be invaded by many thousands of troops intending to overrun their positions.
The Military staff back in Washington DC had asserted that it would take 20,000 men to take and hold Sumter against further encroachment, and it is quite likely spies and sympathizers conveyed this information to the Confederate authorities so that they could prepare.
So Lincoln sent a force sufficient to frighten them into acting, but in actuality, completely insufficient for the purpose of completing it's asserted mission.
And somehow he luckily prevented those forces from actually engaging in a battle in which they would have been destroyed.
Again, that Lincoln sure was lucky that those orders got mixed up.