Therefore, Claudius became emperor of the Roman empire in ... in the beginning of his reign, no one took him serious and he always needed full protection of guards as he was in a dangerous postition.
One of Claudius biggest achievement was when he undertook a military campaign to invaded Britain in....and made this a province of the Roman empire. Which all the other emperors failed to do.
After concurring Britain, Claudius gained much popularity and people starting respecting him more and loving him. He was a good man that was always respectful to his people and the senate.
Besides, invading Britain, he also succeeded to expand the Roman empire by adding Mauretania (north Africa), Thrace (The Balkans), and Lycis (Turkey). He established small kingdoms there.
Besides expanding the Roman Empire, he also managed to improve a lot of public works and infrastructural facilities. For example, he also built the aqueducts: Aqua Claudia, Anio Novus. And he made roads and canals.
Lastly, Claudius made extraordinary improvements to the Judicial system, which made it look more like the one we have nowadays. He was the creator of the cabinet of freedman. He extended the rights of Roman Citizenship and introduced reforms, and reorganised trade. He enlarged the senate to include prominent men from western provinces.