Martin Braun was named after its founder, and was established in 2000. Braun had become a Master Watchmaker in 1991, and his brand was known for astronomical complications.
Martin Braun relocated to Switzerland in 2007 after 52% of the brand was acquired by current owner Franck Muller. Braun left the brand two years later in September of 2009 due to disagreements, and went on to co-found the Antoine Martin brand in 2012.
Jordan Grand Prix Sponsorship?
While publicly accessible details remain scarce, Martin Braun appears to have been a sponsor of Jordan Grand Prix in 2005, the team’s final season in Formula 1. The Martin Braun logo still currently appears on f1jordan.com, and a Minichamps diecast model of a Jordan F1 car was included with the Martin Braun Grand Prix chronograph, which was limited to 250 pieces. Whether or not the watch itself was licensed with the team is not well documented, and no Jordan branding appears anywhere on the model.
A second Grand Prix chronograph (ref. MB823GP-2) was also released at some point, with a limited run of 500 pieces. Details on its release year cannot currently be found.
Tiago Monteiro drives the Jordan EJ15 in 2005. (Photo: by TMWolf, licensed under CC BY 2.0, via Wikimedia Commons)
EOS Grand Prix
According to a press guide provided by Mike Disher on the TimeZone forum, the EOS Grand Prix was announced in 2006 and cited to be inspired by an unspecified “2005 cooperation with the Jordan Formula 1 team”. Like its chronograph predecessor, the EOS version also had Jordan-esque yellow dial accents. It was listed to have a limited edition of 100 pieces, with the option for buyers to reserve a number.
References
https://www.jckonline.com/editorial-article/franck-muller-acquires-martin-braun-33628/
https://f1jordan.com/
https://www.ebay.com/itm/187484311425?mkcid=1&mkrid=711-53200-19255-0&siteid=0&campid=5338788021&customid=&toolid=10001&mkevt=1
https://www.instagram.com/reel/DK5WGtBSnn5/
https://www.watchpatrol.net/listing/1935436/
https://marketplace.watchcharts.com/listing/167775-martin-braun-grand-prix
https://www.catawiki.com/de/l/18133643-martin-braun-classic-collection-grand-prix-chronograph-ii-mb823gp-2-herren-2000-2010
https://forums.timezone.com/index.php?goto=1868099&rid=0&t=tree