Private Baldrick served in the First World War under Lieutenant George and Captain Blackadder, and was killed in 1917 by going over the top (Goodbyeee). Baldrick, like other incarnations thereof, often came up with cunning plans that were either not cunning at all, compromised by his stupidity, or had massive unseen flaws.
When Blackadder was going to face a firing squad for disobeying orders and killing Melchett's carrier pigeon Speckled Jim, Baldrick brought Blackadder an 'escape kit', consisting of a hat with a wooden duck glued onto the top among other impractical things - the only thing Blackadder found of any use was the change of clothes - a Robin Hood outfit. Baldrick's logic was that if he found his way to a French peasant village and they were having a fancy dress party, Blackadder would fit in. However, Baldrik did not consider the eventuality that they would not be having a fancy dress party (Corporal Punishment).
During Blackadder's short lived morale boosting show, Baldrick did a Charlie Chaplin impression, involving balancing a slug on his upper lip. Melchett could not see who he was attempting to impersonate. When the show was cancelled due to George being replaced for the lead role (Melchett wanted to marry George, under the impression that he was a girl), Blackadder fed the slug to Darling saying it was a liquorice allsort (Major Star).
Baldrick had a short career as a navigator in the Royal Flying Core, when he was shot down and nearly ended up teaching nuns home economics in Germany (Private Plane). Eventually, he charged in The Big Push and was killed a year prior to the end of the war.