1590
The serpent, created in 1590 by Canon Edme Guillaume in France was believed to be, historically, the first low-brass instrument. The mouthpiece resembles today's low-brass instruments, although the finger holes resemble a wood-wind instrument's.
1815
The earliest version of the piston valves seen on today's baritones were originally created by Heinrich Stolzel and Friedrich Blumel in 1814- They called it the Stolzel valve. Another variety of this valve was invented by Francois Perinet, who patented his invention in 1839.
1838
The tenor tuba was invented by Carl Moritz in 1838. The look has evolved over decades to now resemble a mini-tuba like instrument, which can be seen here. The tenor tuba and the serpent can be seen to have similarities towards the modern day tuba and baritone.
1843
The euphonium was invented by Sommers of Weimar in 1843 in Germany. This brass instrument closely resembles a baritone, and is used widely in ensembles.
1950
The first low brass ensembles were featured in England.
1973
The T.U.B.A. (Tubists Universal Brotherhood Association) was formed officially in 1973 with a goal to enhance and maintain the overall tuba and baritone family. This included the production of better instruments and a greater amount of baritone/tuba-directed pieces. This association now has a positive affect on many aspects of these two instruments.