Welsh skipper Jamie Howells spearheaded the visitors' charge as he helped himself to 12 points, including one of the three second half tries.
By the end, the Welsh side had outscored their hosts 4-1 in the try department and were worthy winners against much higher ranked opposition.
"It all went to plan in so much as we got the right result. We expected a physical encounter and we certainly got one," admitted Howells.
"We kept believeing in the game plan and at half-time we stressed the importance of putting phases together. Once we did that we created chances and scored tries."
It was Narberth wing Tom Bonnell that grabbed the first of the Welsh try quartet and Howells added a penalty to make it 9-8 at the break.
Then Wales cut loose with three further tries to one consolation effort from the home side.
Narberth centre Steve Martin, his co-centre from Whitland , Emyr Williams and Howells crossed the home line and the skipper added tow conversions to complete an historic win.
The Germans' had beaten the Ukraine and the Netherlands in their last two European Nations Cup outings and were using the match as a warm- up for their next Nations Cup Division 1 outing against Spain on 15 November.
Wales Clubs XV v Germany: Matthew John (UWIC/Blues/Scarlets); Tom Bonnell (Narberth/Scarlets), Steve Martin (Narberth/Scarlets), Emyr Williams (Whitland /Scarlets), David James (Blackwood/Dragons); Jamie Howells (captain, Bargoed /Dragons), Andrew Davies (Narberth/ Scarlets); Ross Jones (Bargoed /Dragons), Daniel Smith (Narberth/ Scarlets), James Huntley (Rhiwbina/Blues), Jamie Noble (Newbridge/ Dragons), Alex Jenkins (Narberth/Scarlets), Chris James (Narberth/ Scarlets), Shaun Miles (Ammanford/Scarlets), Colin Davies (Cardigan / Scarlets).
Replacements: Alun Davies (Carmarthen Quins/Scarlets, Rhys Cleverley (Beddau/Blues), Sion Dafydd Waddington (Pentyrch/Blues), Chris Strick (Felinfoel/Scarlets), Carwyn Morgan (Pill Harriers/Dragons), Matthew Lewis (Builth Wells/Blues), Matthew Davies (Narberth/Scarlets)