I'd need to see the plant before I'd settle on wilt being the problem. Clematis wilt typically attacks young plants, seldom one that has been established as long as 6 years. And it is usually never fatal. In my old garden, a healthy percentage of my 40+ clematis vines were nursery returns attributed to wilt that I rescued and brought home and cosseted for awhile before replanting. And several of the vines at my new garden are the same - all doing just fine.

There are other clematis issues that are frequently attributed to wilt that are not. Most often it is some sort of unfavorable environmental condition. I'd be much more inclined to consider this as a problem, especially with a plant that has only been in the ground for 3 days.

International Clematis Society - wilt

Gardengal, here are a couple of pictures. Sorry for the blurriness. This damage happened overnight, as these leaves were healthy yesterday.

Can you take several steps back and take another photo so we see its environs? Can you also add information on where you are to your profile so we have some idea of growing conditions? Anything you can add would be helpful as well, such as how you planted it, what the soil is like, etc. Just from those photos, it looks really close to the wall, so last year's vine might have had issues from high pH if there is new concrete, or insufficient moisture if it is under the eaves of the house, etc. So more info is needed. My greatest clematis killer is a small mouse-like rodent called a vole. They eat just above or below the soil line, and seem to love clematis to the point that I now plant in circles of 1/4" hardware cloth (wire mesh).

To add zone and location info to your profile,

Go to Your Houzz in upper right of every page, click Edit Profile, and on the left side click advanced settings. Well down the advanced settings page is a blank labeled Climate Zone for Garden Forums along with a link to find your zone.

Then return to the top of the page and click Done Editing.

For the new plant with wilting in such a short amount of time, I am inclined to think that you have some type of vine damage , whether it is cut worms, wind damage, or some damage caused by transport and planting. IME wilt doesn't effect type 3 clematis like Jackmanii.

I am in zone 5a.
This trellis is about 1 foot from the concrete foundation, so right at the drip line past the overhang of the house. Same location as the Jackmanii that had previously grown without issue (until last year). This is the north side of the house, and has shade from morning until late afternoon, then lots of sun until evening. The foundation does not gain a lot of daytime heat, so I don't think it's that.
Soil is generally loose and not clay. There is a small amount of pea gravel mixed in.

I apologize for not being more clear in my original post. The cultivar that I planted to replace the Jackmanii is actually a Carnaby, which I think is a type 2? (not certain)

Weather-wise since I planted it: I watered it when I planted it. We had rain the next day. The past two days have been consistent 20+ mph winds, with occasional gusts in the 40 mph range. Temps on planting day were in the 70's, but we've cooled to the upper 50's since then.

The vines did not show any breakage below the wilted/turned areas. All vines were intact.

About voles: we do have them on occasion, but there is no evidence of them here (and they never bothered the other clematis--the liked the flower bulbs best).

Sorry, but I disagree with almost all of the above post except for the part about burying the vine deeply. Peat moss will unnecessarily acidify the soil and clems prefer a very slightly acidic to slightly alkaline soil. And I wouldn't subject ANY plant to Miracle Gro soil. Adding all those different ingredients is just asking for soil interface issues and the potential of creating a bathtub of overly moisture retentive soil that can lead to root rots.

As long as your soil drains well, regular garden soil works fine but you do want to dig a very generously sized planting hole and amend well with compost. If your soil doesn't drain well, you need to find a location that does or plant in a raised bed.

And not all clematis varieties require 6 hours of sun. Some are quite shade tolerant and some need to be sheltered from midday sun to retain coloring.

Type 2 clematis are effected by wilt sometimes. They usually grow out of it, so I would prune off the effected stems to below the wilt and wait it out.

Like gg48, I plant in native soil, and with the exception of those clematis eaten by voles, mine do just fine. I amend the entire bed before I plant anything and then top dress with compost most years.

I do amend generously with compost and my beds have been composted so much over twenty years that there is no native soil alone left...but I would never use Miracle Gro soil. I rotted out my entire greenhouse one year with it, it does not drain well at all.