Why does the play shift back and forth from national affairs to the comic world of the taverns?
There are two different domains in Henry IV: Part I, the "macro" realm of political events and the "micro" world of Eastcheap's taverns to which Falstaff and his rowdy crew belong. Shakespeare exploits the contrast by shifting the scene back and forth between these worlds. The technique has three broad functions. First, it provides Henry IV: Part I with a variable tempo that only increases its momentum. Events at the level of national political crisis move along at breakneck pace; incidents at the "micro" level unfold at a leisurely pace and appear almost arbitrary. The idleness of the latter highlights the urgency of the former. Second, the technique permits Shakespeare to capitalize on parallel developments. Thus, for example, we can contrast the touching adieu of Hotspur to his wife, Lady Percy, with the comic farewell of Falstaff to his favorite bawd, Doll Tearsheet. Third and most important of all, the movement is integral to the core theme of Henry IV: Part I, Hal's development from a companion of wastrels into England's great warrior-king, Henry V. In the concluding work of the four-play series, Henry V, Hal, now England's king, is fully capable of directing his nation through crisis and benefits from his knowledge of the "common man." Hal must spend time with Falstaff and the rest to gain insight into the lowest of his subjects, yet he himself is destined for the "macro" world of national glory.