Well, just running through some famous women leaders:
Cleopatra was probably overcome by events already in motion. Her choices went sour, but not always by her error.
Catherine I of Russia continued reforms her husband (Peter the Great) had begun and certainly didn’t start any more wars than Peter had.
Catherine II of Russia was involved with more wars, but that was a continuation of the Russian policy of the preceding 150 years and hardly something she started on her own. Under C II, Russia expanded its territories considerably.
Elizabeth I of England was embroiled in already-existing conflicts with Spain and the Netherlands, but can hardly be claimed to have started those wars. During her reign, England grew both in prosperity and power.
Victoria of England hardly set policy. England continued a long tradition of warfare and conquest under her ministers, but that hardly was encouraged or impeded by her presence.
Margaret Thatcher had one small war. I think she went too far in some of her social restructuring, but much of her economic platform was necessary to escape the dismal 70’s and she can hardly be accused of ruining Britain.
(There was also a semi-legendary queen of an English tribe, whose name I cannot remember, who actually led her troops in battle. However, since she was defending her realm against an invasion, I hardly think it’s fair to mock her warlike nature.)
Catherine de Medici of France was embroiled in the religious wars of the post-Reformation and was involved in numerous power struggles in France. You might charge her with too many conflicts and “ruining” the country.
Isabella of Spain was (with her husband) inclined to warfare and conquest. She certainly did nothing to further humanitarian goals with her expulsion of the Spanish Jews and the establishment of Torquemada’s Inquisition (possibly to revoke the debt she and her husband owed Jewish fananciers for helping them “liberate” Spain from the Moors). On the other hand, from a materialistic perspective, she did not “ruin” the country and we cannot evaluate her without cnsidering her husband (who was king, after all).
Maria-Theresa of Austria was involved in several wars, but did not actually initiate any.
Elizabeth of Hungary was not involved in any wars that I remember. She was deposed for spending too much money after her husband died. Of course, since the object of her spending were the poor of her country, it just may be possible that she was deposed for spending money that her brother-in-law wanted to spend on himself.
Margaret of Denmark actually brought about the first serious unity of the Scandinavian countries through dilomacy. It was probably the force of her personality, because it fell apart at her death, but she was not particularly warlike.
Lucrezia Borgia has a pretty bad reputation (possibly much of it undeserved) because of the corruption that surrounded her–but she was never a head of state.
The nations that these women led were frequently involved in wars during their reigns. Of course, since most of them ruled at a time that the sole purpose of nations seemed to be warfare, that doesn’t exactly lend credence to the idea that they began the wars.
I’d ask your know-it-all friend to put up or shut up.
Tom~