The present paper introduces a corpus of Dutch Renaissance poetry which was automatically annotated by using neural networks. The analysis of the annotations provides a clear picture of the process of implementing the new poetic form into Dutch poetic tradition, and of its different stages. The development of iambic metre was a gradual process that required various attempts; this can be well observed when comparing Dutch poems from a 100 year time window. While syllabic instances can be observed among the first attempts, most of the earlier poems are not isosyllabic and have a rather varied syllable length. This study shows that isosyllabicity developed together with iambicity. Finally, automatic poetry annotation allows for testing and validating theoretical hypotheses and for investigating literary questions with the aid of large amount of data.