"On one side of the river the slogan was 'Kill the Gringos'; on the other it was 'Kill the Greasers.'"

It is often useful, when contemplating contemporary snake pits -- such as the problem of "border security" between the U.S. and Mexico -- to recall that not so long ago, life was much, much messier. In "A Troubled Past: The Army and Security on the Mexican Border: 1915-1917," published in the July-August issue of Military Review, military historian Thomas A. Bruscino takes us back a century to a time far more chaotic and violent than today.

The U.S. Army not only had to deal with constant deadly border raids, including some led by the notorious Pancho Villa, but was also plagued by local vigilante and law enforcement groups motivated by racial antagonism. Today's Minutemen have nothing on the Texas Rangers.

The Texas Rangers had the ostensible responsibility for keeping order in the state, but a corrupt and inefficient governor had hobbled the organization. Just as the situation on the border grew worse, the force became inexperienced and inept, and Rangers participated and even led attacks against Mexican Americans. In August, civilians in Texas organized the Law and Order League, one of several vigilante groups. These groups confiscated weapons and property, threatened Mexican Americans, and beat, shot, and lynched suspected bandits. In September, one of the groups shot and killed 14 Mexican Americans near Donna, Texas, and left the bodies in a row as a warning to the bandits.

Further complicating the Army's situation were orders from Washington prohibiting U.S. soldiers from crossing the border while in pursuit of bandits. Negotiating the "mishmash of border security, local violence, guerrilla warfare, racial politics, and state diplomacy" was not easy. Ultimately, writes Bruscino, border disputes ended up solved via treaty rather than armed force, but for "for that time in the 1910s when the Army played the key role in trying to provide stability and security along the border, the situation became very messy and nearly degenerated into war."

In June 2006, U.S. military forces were assigned to the border to assist the Border Patrol in dealing with illegal immigration and drug smuggling. What lessons can be learned from the experience a century earlier?

Where then in this situation is the major area of concern for the military? The same place as it was in the 1910s: escalation. The border region is peopled with individuals of varying nationalities and national allegiances, and those allegiances can fuel intense emotions. Local authorities have their own agendas, which can be at cross purposes with the concerns of the national government, and volunteer law enforcement or vigilante groups might choose to act outside of local official policies. The presence of international boundaries means that local authorities must work with national-level diplomats to find solutions to disputes. The danger only grows when the military moves into the area...

When the military is involved, there is a great temptation to use force, as everyone discovered in the 1910s. But as everyone also discovered in that tumultuous decade, the use of force along the border can have dramatic and very negative effects.