Naval brigades in the Napoleonic Wars and at Torres Vedras

In which large war did naval battalions or brigades have their greatest effect?

The Napoleonic Wars are the preferred answer, although naval divisions also mattered in the First World War. Naval brigades could help turn battles and hold the Lines of Torres Vedras while Wellington's army recovered.

Naval divisions made a substantial contribution in the First World War. The judgment here favors the Napoleonic Wars for the influence of smaller naval brigades. Their work in the Lines of Torres Vedras helped give the army time to rebuild, and Wellington is said to have requested that support. The comparison concerns the effect of forces in particular campaigns rather than simply their size.