DORTMUND, Germany -- Borussia Dortmund fans protested their club's controversial sponsorship deal with an arms manufacturer during the team's Bundesliga opener on Saturday.

The second half of Dortmund's match against Eintracht Frankfurt started against a backdrop of banners criticizing Dortmund's three-year sponsorship deal with Düsseldorf-based Rheinmetall -- the world's largest maker of artillery ammunition.

"Not for [expletive] armaments industry," read one sign under a giant banner that simply cursed Rheinmetall with an expletive. "Money first, values second," read more banners, while another said, "Our values rolled over by a tank."

"Borussia connects, Rheinmetall kills," said another couple of banners.

The fans were also audibly quieter than usual once the game resumed, as if withholding their support.

Campaigners set up a dummy tank outside the stadium before the game, when an activist wore a mask with the face of Rheinmetall's CEO, Armin Papperger, while holding a red card.

On Wednesday, supporter association Südtribüne Dortmund had signaled the intent of more than 90 fan groups to make their opposition to the deal clear at the start of the second half of Saturday's game. The association encouraged fans to bring placards and banners criticizing the deal.

The association also criticized the timing of Dortmund's announcement of the deal -- in May, three days before the team lost to Real Madrid in the Champions League final -- saying the news came as a "bombshell."

Rheinmetall expects to make record group sales of around 10 billion ($11.1 billion) this year.

In February, it announced the construction of a new factory at its existing site in Unterluess in northern Germany, with annual production capacity for 200,000 artillery shells, 1,900 tons of explosives, and possibly rocket engines and warheads.

Founded in 1889 as "Rheinische Metallwaaren- und Maschinenfabrik Actiengesellschaft," the company was one of Germany's biggest armaments manufacturers during both World Wars. It made use of forced labor during World War II.