There is little information thay one can find about this grape except that it comes from the same cross as Marechal Foch and Leon Millot. The Mgt 101-14 x Goldriesling cross was made by Eugene Kuhlmann in France in the early 1900's. This variety is said to be earlier ripening than Leon Millot and in my experience with this variety in Edmonton it ripens very early about 2 weeks ahead of St. Croix and a week ahead of Leon Millot. However, we rarely get any grapes on our Joffre vines in Edmonton as the winters in are too cold and the vine often dies back to the ground.
This variety is very disease resistant, similar to that of Foch, and cold hardy to about the same as Leon Millot -27c. The clusters and berries are small but there are usually 2-3 clusters per shoot. The juice of the Joffre berries resembles that of the other Kulhmann hybrids (good read on the kulhmanns), with a little less pronounced berry fruit expression. However, on the chemistry side the juice can reach a high brix in the 23-25 brix range while the acid levels are better than Foch which can often be quite high.
Like Leon Millot and Marechal Foch, the Marechal Joffre grapes are quite versatile and can be made into various wine styles from rose, to light cafe reds to big reds and even port. However, in Nova Scotia where the vine is most widely grown in Canada, the grape has primarily been used as a blender. While not usually made into a varietal, some that have done so have found the wine quite appealing. see link
Perhaps its greatest attributes are its disease resistance and cold hardy qualities, but best of all it will always ripen a crop in short season areas - see link. This is probably why it is valued as a blender because even in the marginal years, when other varieties produce less than optimal crops, it will produce and make a nice base for blending.