The complex structure of military operations has led to huge variations in military uniforms and consequently in military headgear. From the ceremonial hats of the parade ground to the more practical headgear used on operations, soldiers experience a wide range of headgear. Many of these hats have changed little since World War I in the early 20th century, and some go back even further, to the Civil War days. This is because the military is steeped in tradition and has a strong sense of sentimentality, particularly in its uniforms.
The campaign hat is the wide-brimmed, circular hat famously worn by park rangers. In the United States military it is used by drill instructors, although regular soldiers have been issued them in the past. Military training instructors -- MTIs -- wear navy blue campaign hats. This is adorned with the Great Seal of the United States, which is centred at the front of the hat.
The garrison cap is the long cap, folded down the centre, traditionally worn by both British and American soldiers throughout most of the 20th century. It was originally issued to troops fighting in Europe in the First World War, as it was easy to store when a helmet needed to be worn. Following World War I, the U.S. military began to develop the garrison cap, giving it different-coloured piping to delineate rank and branch of service.
For actual combat operations, a helmet is preferred. The practical reasons behind this are obvious; helmets give your head more protection from bullets and other flying debris. The U.S. Army has now adopted the modular integrated communications helmet -- MICH -- for its operations. The MICH offers a better range of motion than standard helmets and the TC2000 model has a communications device built in, allowing troops to coordinate their manoeuvres.
The traditional sailor's cap -- also known as the dixie cup -- originated in the pre-Civil War days. Introduced in 1852, the basic hat design has changed only slightly over the years, despite complaints from sailors that it doesn't cover the ears, leading to some discomfort in freezing conditions. To wear the cap correctly, the U.S. Navy has come up with a special technique: Place the cap on your head and place your pointer on the tip of your nose and your middle finger on the top of the nose bridge. The third finger should now be pointing to a spot on your forehead; this is where the bottom of the cap should be.