Naval gunfire on the First World War's coastal flank

How effective was naval fire support in First World War trench warfare, and what if battleships had later gun ranges?

It was devastating inside its limited reach; later-range guns would greatly enlarge the zone in which naval forces could disrupt land operations.

Naval fire support was extremely effective within reach of the coast. Early in the war, German forces attempting to cross apparently open Belgian ground were met by concentrated six-inch and other naval gunfire and withdrew under its weight. Post-Second World War ranges would extend that influence much farther inland and make the coastal flank still more dangerous.