The second in a series of books detailing the air battles and wartime activity over Britain focuses on Hertfordshire. It is now 222 years since the Italian diplomat Vincenzo Lunardi landed his balloon there, accompanied by his dog, cat and a caged pigeon. One of the first fatal military aircraft crashes happened in the county in 1912, and the first Zeppelin to fall in Britain came down at Potters Bar in 1916. The famous DeHavilland family based their aircraft manufacturing business at Hatfield, where the Mosquito was designed and built, Luftwaffe bombers were shot in the county and American bombers were stationed at its airfields; all have contributed the county's rich aviation heritage. It is possible in many counties to walk around unaware of many historical events and happenings in Hertfordshire as so few have attracted permanent memorials. The aim of this work is to make the reader more aware of the history on their door-step. By utilising some of the eye-witness accounts, no longer available first hand with the passing of many witnesses, and wartime archives, it hopes to stimulate further personal research avenues to be undertaken in the future; this can be immensely satisfying, as one never quite knows where such an undertaking may lead to.