Spain had the better of the early exchanges and led 22-18 after the first quarter before their opponents got into their stride and led 41-34 at the break.
With 10 of the British squad playing in Spain last season, both sides know each other well, and the Tokyo Paralympic bronze medallists used their experience to draw fouls from their opponents to upset their momentum.
Spain did cut the lead to one point (43-42) in the third quarter but Terry Bywater quickly responded and baskets from Jim Palmer and Manning extended the lead, and they maintained their advantage.
“It was all about getting out there today and getting the job done,” said Manning.
“I was confident that if we played and stuck to our game plan, we would be in a good position. But you can’t take anything for granted. Spain are an awesome team.
“Obviously we’ve got lots of friends in the opposition team, their head coach is my club head coach, and we always knew he wasn’t going to come out and give it to us.”
Wheelchair basketball is one of 10 Para-sports combining for the first time to stage their European championships together.
In the archery event, Britain’s David Phillips and Cameron Radigan won gold in the men’s recurve doubles, beating Turkey 6-2 in the final, while the compound women’s doubles team of Jodie Grinham and Jess Stretton won bronze after a 133-124 success over Poland.