Thanks gew8805.
And for the benefit of Lawrence and others, may I point out that I have no knowledge whatsoever of canteens, Civil War vintage or otherwise. My judgement was based on observation of the materials, nothing else, hence the proviso "as far as I can tell from the photos", which I usually add, but regrettably appear to have omitted in this case.
Styles can be imitated, marks can be falsified, but material ageing is difficult to fake. Cloth and leather are notoriously difficult to preserve, and museums such as the Victoria and Albert have problems with materials merely being exposed to light, temperature variations, and the natural humidity of the surrounding air. Materials that in many cases are younger than the American Civil War. Give the V&A a call if you don't believe me.
Of course, an original artefact may have been preserved at a constant temperature in darkness with zero humidity - such as may actually occur with grave goods - but for the articles with which we are concerned on these forums, that is, to say the least, extremely unlikely.
So look at what you see. If it looks like it was made last week, chances are that it was.