This paper constitutes an empirical investigation into the diachrony of clitic climbing (and consequently restructuring) in French based on data from a novel corpus of legal texts, as well as a theoretical analysis of the loss of this phenomenon from the history of French. We show that clitic climbing was obligatory until the Middle French period, until its eventual loss before the start of the 19th century. Assuming that clitics are φ-heads that AGREE with v, we take restructuring to be monoclausal, despite apparent counterevidence where a subordinator or a Wh-item intervenes. We propose that restructuring is a necessary but not sufficient condition to clitic climbing, the latter depending on whether the upper v-head bears a set of unvalued φ-features. We associate the loss of clitic climbing to the loss of interpolation (i.e. the order [clitic-XP-V]), as we show that both constructions are available when cliticisation is a phonological mechanism only. In Modern French however, clitics are necessarily proclitic and verb-adjacent which indicates that cliticisation is syntactic. Lastly, we propose that French never lost restructuring, but instead it lost most transparency effects associated with it (such as clitic climbing), while retaining others (such as long passives and quantifier climbing).