War is always exciting, especially if you don't have to sit around too much but get to blow somebody's head off and then come on home, so the new "Renaissance Art of War" exhibit at the Folger Shakespeare Library should appeal to many.

The best thing that has happened, warwise, was the introduction of gunpowder which caused a revolution in the condudct of war in the 1500s.

As the exhibit (various cases of rare books open to drawings, etc., and complete with labels explaining the various copies) makes clear, the armored knights of the Middle Ages disappeared and the infantry became the true arm of Mars.

In naval warfare, the change was especially dramatic.

At the Battle of Lepanto (1571), the ships were oared and in Classical periods, the head-on attack was all there was. But only a few years later, when the Armada sailed against Elizabeth (1958), there was a completely new system of sails, not oars, and broadside fire from big guns was the technique.

Lepanto is the battle in which the great author, Cervantes, got the bones of his left hand fractured by a Turkish bullet. The effect of this battle on his masterpiece, "Don Quixote," is incalculable.

Lepanto also had a certain effect on politics and fortunes of the day, though few can now recall exactly what.

Spain, as the exhibit shows, was preeminent in Renaissance warfare, in the sense that her enormous empire required a continuing cadre of military service, and not surprisingly produced a certain manner of exceptional captaians.

The English relied more, in the 16th century, on people like Drake, when they were not playing bowls, and the French had internal power struggles and St. Bartholomew's Day.

Shakespeare, in "King Henry V" ("O God of battels steele my souldiers harts") did much for any doughboy's morale, if not for his spelling, and a beautiful early edition of the play is displayed.

The Italians were highly elegant and highly disorderly during the Renaissance. The rise of the great Sforza family is noted in the exhibit (they had been shepherds or something of the kind) and both Castiglione and Machiavelli are represented by rare volumes. These are still importaant guidebooks to Washington and most people who have been employed more than five years running owe great debts to those writers.

The "problem" of morality, in war, accounts for a full case of rare volumes. Many people with a taste for conundrums have exercised their fancy over the years on the subject of just wars, etc., and while the issue has never had any relevance to actual events, still those with leisure have long enjoyed their speculations.

The exhibit is quite short on scenes of gore, which made Vietnam so successful on television, and it is perhaps the most serious flaw in the show. Museum shows during the Christmas season (this one runs until April 1) are traditionally colorful, but this is black and white.

The exhitbit hall closed at 2:45 yesterday afternoon to prepare for a party, but usually the hours are 10 to 4:30 except Sundays.