These two books -- neither of them known to any considerable American public-have a timeliness today that may give the impetus they need. For both deal with the sort of guerilla warfare Hemingway writes of in For Whom the Bell Tolls, Caldwell in All Through the Night. The Gun was published in July 1933, as an isolated bit of thinly fictionized history, an episode in the Spanish campaign of the Napoleonic Wars when guerilla bands, under the leadership of a patriotic priest, captured a gun and moved it over incredible barriers. Rifleman Dodd presents yet another panel in this guerilla warfare, against a Fortuguese background, and another lone exploit, in which a rifleman, cut off from his company, joins forces with the guerillas, dodges the French while causing them countless inconveniences, and finally, almost single-handed, destroys a pontoon bridge. The irony of the outcome fortunately is known only to the reader -- while Dodd gets back to his men. Here, in pictures of scattered pinpricks in a war for world domination more than a century ago, are parallels which carry vitality today, parallels in mood and tempo and portraits of conquered peoples. Lacks the pace and gusto of Forester's Captain Hornblower.