In the weeks leading up to the 2016 US presidential election, the global expectation was the victory of Hillary Clinton. However, the shocking result saw Donald Trump and the Republican party emerge as winners. This unexpected outcome sparked speculation about the influence of microtargeting on social media on the election. This study investigates political behavioural targeting (PBT) in the election, specifically on Facebook, and the extent of public awareness and concern about PBT. It also reviews the history and origins of PBT. An initial collection of 1000 advertisements was broken into themes for analysis, and then a visual rhetorical analysis was applied to a subset of 50 advertisements. The results reveal that PBT was extensively used, with significant Russian involvement. The findings suggest that PBT, delivered via Facebook as a trusted platform, effectively persuaded and influenced voters, often without their knowledge. The impact of PBT on the 2016 US election outcome underscores its potential power and covert role in shaping election results.