https://www.abbevilleinstitute.org/...ers-said-the-black-confederate-myth-examined/
The earliest mention I have found that uses the word “soldier” in relation to black Southerners is in an article about these men, and it’s not the only time we’ll see that term applied to black Southerners.
THE FREE COLORED SOLDIERS. – We some days ago mentioned that the Creole free colored population downtown had taken the war question into consideration, and determined to offer their services to Gov. Moore, for home defence. At the meeting held for this purpose, some 1500 men were present. With one voice and with the greatest enthusiasm they agreed to offer themselves, and did so. The Governor accepted them, and they are now forming companies, as their fathers and grandfathers did in 1814 and ’15. Should their services be needed, they will be among our hardest and best fighters. Jordan Noble, better known as “Old Jordan,” the Drummer of Chalmette, is raising a free colored company; and we learn a similar company is being organized in Jefferson City. When the down-town free colored men form their regiment (and it will be a rousing one.) they will make a show as pleasing to all, as it will be surprising to many of our population. We will give further particulars as the organization progresses. – New Orleans Daily Crescent. April 27, 1861
Note the use of the term 'colored' and not black. This is important because the CSA consistently reject men who appeared to be black as slaves as soldiers. This makes the use of 'black' in the term 'Black Confederate' questionable.
These men would of course go on to form the First Louisiana Native Guard, a group of free black and creole volunteers. This group got quite a bit of press over the course of their existence and even after they disbanded, as they were brought up by Union General Benjamin Butler who used the exact words of Louisiana Governor Thomas O. Moore’s order praising the group’s patriotism and authorizing their existence as a military unit to try and silence Southern critics of Butler’s own enlistment of locals blacks as soldiers for the Union.
The so-called 'Confederate soldiers' only fighting was for the Union, also the only nation to arm and provide uniforms.
Modern critics of my even mentioning these men would say that they were not in fact Confederate soldiers, and to the extent that they were Louisiana state volunteer troops rather than enlisted in the Confederate army, that is true, though in response I would have to ask just what uniform they wore, and which side they were aligned with. The answer seems obvious. Many contemporary newspapers did not make the same fine distinctions as some modern historians either. To them, an armed and uniformed man in any Southern state’s military was considered Confederate.
Because the CSA rejected them as 'soldiers', that appears to support the notion they were not Confederate 'soldiers'. The State of Louisiana was unsure they were soldiers, refusing to arm them or provide uniforms initially, formally disbanding them on February 15, 1862, then restating them on March 24, 1862 issuing them a few ancient flintlock muskets with a final disbanding on April 25, 1862, when the so-called 'Confederate soldiers' refused to rejoin the Confederate forces that abandoned them and New Orleans. If neither the CSA nor the State of Louisiana regarded them as soldiers, why should we?