The best and most thorough sources are Jack Bauer, "The Mexican War" Lincoln: University of Nebraska Press, 1992
John S.D. Eisenhower, "So Far from God: The US War with Mexico, 1846-1848," New York: Doubleday, 1989.
The most detailed study is Dwight Clarke, "Stepehn Watts Kearny: Soldier of the West" Norman, University of Oklahoma Press, 1961. It is a bit dated and it is a biography of Kearny, but it by an accomplished and thorough historian.
As a military historian and professional soldier let me lay out some military aspects for my argument; aside from all the emotion of Hispanic and Mexican war agression, war is war, and that is what I am most interested in.
Many people look at fight at San Pasqual as a Mexican/Californian victory because Kearny lost 21 dead and many wounded, including himself. That the battle was sloppy and poorly managed and led, and that the Americans had to enter into a defensive operation that led to a seige two days later at mule hill. These are all facts.
Several factors to answer truthfully and honestly as a military analyst:
Did Kearny have the initiative and commence the battle? Did he chose when and where to fight? YES
Did Kearny and his force retain combat power and unit cohesiveness after the fight? YES
Did Pico react to Kearny or did Kearny react to Pico? In other words who had the initiative? Kearny did.
Which force retained and occupied the battle area? Kearny
Could and did Kearny continue his mission, which was to reach San Diego? YES
The next day, 7 December Kearny's dragoons drove off and killed several lancers, so Kearny in fact had combat power, freedom to manuever (initiative) and continued his mission.
On December 8, Kearny realized that his force was suffering due to teh wounded and poor mounts (horses and mules) and he could not continue so he decided to conduct a defensive operation. He did this more out of logisitical issues and not Pico's harrassing his force.
So, Kearny chose when and where he would stop, and he sent for re-enforcments to Stockton in San Diego. Two days later re-enforcements arrived. During all this time he was able to defend and defeat any attempts to destroy or capture his force.
Analysis and historical examples:
If we judged every general on poorly executed battles than we would not have many generals left. Give me an example of a perfectly executed battle?
We have to separate the fight at San Pasqual (6 Dec) from the siege of Mule Hill (8-11 Dec) they are two different operations, but unfontunately most people see them as one operation or battle. They were separate actions but part of the same campaign, a campaing that eventually conquored California. If this true that it was one battle, then we must say that the Germans initially defeated the Americans at the battle of the Bulge in 1944, surrounding the 101st Airborne Division for three weeks, until re-enforcements saved them, then can we say the Germans won? Once Kearny and Stockton combined forces they fought until final victory was achieved. In 1879 the British lost 1,200 men to the Zulus at Isandlwana in the morning then the Zulus were defeated at Rorke's drift later that night and the next day: two separate battles, one campaign just as San Pasqual and Mule Hill.
Because Kearny lost more men (accounts vary widely as to how many Californian lancers were killed and wounded, because the lancers quickly carried off their dead) so that convinces most people. Casualties is perhaps the worst indicator of decisive victory or defeat.
Examples:
Battle of Heraclea took place in 280 BC between the Romans against the Greeks under King Pyrrhus of Epirus. Thus the Greeks won but lost much of their army and it did not achieve their war aims, thus to this day we use the term "Pyrrhic Victory" meaning a victory that was not substantive.
Battle of Bunkerhill, June 17, 1775, Colonists lost some 450 men to the British 1,100 and General Gage said "another such victory and we will lose the war." Yet, the British took the hill and won the engagement though the defeat gave the Americans a great morale boost.
Casualties are the least important factor.
Conclusion: the battle was not decisive. Decisive in military parlance means, clear and obvious, not that the battle won the war. Robert E. Lee won a decisive victory at Chancellorsville only to lose a decisive victory at Gettysburg two months later. Neither battle brought the war to a close.
The battle was quick, deadly, in the dark, indecisive but Kearny and the Americans won the battle in light of the factors I have explained above.
So, this is the last I am going to deal with this situation. Excuse my ignorance of how to communicate in Wikipedia and make changes and revisions. I am not a vandal. I saw an error and incorrect interpretation and I edited it. I hope this helps.
Braverifles!!!
By the way, Braverifles is the regimental affiliation I served while in the Army.