Not according to the Supreme Court, which upheld the constitutionality of the acts in Ford v Surget. The Davis regime had it's own version called the The Sequestration Act passed in August 1861. That authorized the permanent seizure of the real and personal property of "alien enemies" within the confederacy and affected those who remained loyal to the union. I guess those were constitutional because Davis said they were. No fine line needed by the Davis regime where legal precedents were concerned, or a supreme court either.
Ford addressed the legality of the Sequestration Act passed during the Lincon regime. The act applies to existing civilian debt owed to an enemy - not government/military seizures made during war.
[T]here could be no doubt of the right of the army to appropriate any property there, although belonging to private individuals, which was necessary for its support or convenient for its use. This was a belligerent right, which was not extinguished by the occupation of the country, although the necessity for its exercise was thereby lessened. However exempt from seizure on other grounds private property there may have been, it was always subject to be appropriated, when required by the necessities or convenience of the army, though the owner of property taken in such case may have had a just claim against the government for indemnity. ...From Mitchell v Harmony:We fully agree with the presiding justice of the Circuit Court in the doctrine that the military should always be kept in subjection to the laws of the country to which it belongs, and that he is no friend to the Republic who advocates the contrary. The established principle of every free people is, that the law shall alone govern; and to it the military must always yield. We do not controvert the doctrine of Mitchell v. Harmony, reported in the 13th of Howard; on the contrary, we approve it.
Justice Field, Dow v. Johnson, 100 US 158, 168, 169, (1880)
There are, without doubt, occasions in which private property may lawfully be taken possession of or destroyed to prevent it from falling into the hands of the public enemy; and also where a military officer, charged with a particular duty, may impress private property into the public service or take it for public use. Unquestionably, in such cases, the government is bound to make full compensation to the owner. Chief Justice Taney, Mitchell v. Harmony, 54 How. 115, 134 (1851)Before and after the war, the courts held that property cannot be taken by the goverment without compensation for said property (see Amendment 5).