You don't need to look any further than the American Civil War to find an excellent case study in the disadvantages of depending on a volunteer army. During the first few weeks of the war, Southerners had flocked to join the Confederate army in the tens of thousands. By the end of 1861, however, morale had taken a steep dive and roughly half the Confederate troops suddenly had the option to leave the army with the expiration of their one-year enlistments.
In an attempt to stave off this massive troop drain, the Confederate Congress passed legislation to reward reenlisting soldiers with $50, a 60-day vacation and the freedom to change regiments and elect their own officers [source: Wert]. In the end, however, the fledgling government was forced to institute a draft.
Similarly, critics of the United States' current volunteer army point to the military's continuing struggles to meet its recruitment goals -- a fact often attributed to continued operations in the Middle East. Of course, the U.S. Military has reserve units to call on, as well as all those selective service cards in wallets around the country. Should the U.S. need to reinstate the draft, there are millions of men aged 18 to 25 already in the system.
The U.S. Military has been forced to lower its recruitment standards, as it simply can't afford to turn as many volunteers away. Commentators have suggested recruiting more women, ending "don't ask, don't tell" and enlisting more non-citizens, in addition to further lowering standards and raising enlistment incentives.
In addition to struggles to bring in new blood, the U.S. Military continues to fight to retain trained officers with higher bonuses to keep them from taking their military leadership experience out into the civilian business world.
Demographic changes threaten both conscription and volunteer armies. If a nation's birth rate drops, it reduces the overall recruitment pool. Whether you intend to lure in new soldiers with a legal summons or a lucrative singing bonus, you only have so many citizens to draw from.
And what does a nation do then? Well, in 15th and 16th century Europe, the popular choice was to employ foreign mercenaries, who often proved dangerous and difficult to manage -- especially when not paid. This led to a third option: conscripting members of the peasant class to serve under nobleman officers. In doing this, the powers of Western Europe slowly wore down the social structure that separated nobility from common man -- which in turn led to the rise of the large, integrated volunteer army.
Explore the links on the next page to learn even more about volunteerism and the military.