Modern howitzers are commonly either self-propelled or towable. During World War II, a 75 mm "pack" howitzer was in common use. The 75 mm howitzer could be disassembled into several main components and carried by mule through very difficult terrain. Howitzers of such small caliber have generally been abandoned in favor of larger guns with greater capabilities. Modern howitzers fire 105 or 155 millimetre diameter shells at a maximum rate of approximately 10 per minute.
Small howitzers can be towed by a utility vehicle such as a humvee or airlifted by helicopter. Most are towed by five-ton or larger trucks. Recent developments favour self-propelled artillery because of it shrapnel protection.
Howitzers used by the United States armed forces include:
The Big Bertha was a large, 42 centimeter howitzer used in the German push of 1914. The gun was based on a similar 42 centimeter gun used for a short while by Krupp for the German military.
That similar, older 42 centimeter gun was based almost completely on a gun designed by Louis Gathmann in the late 1800s. Louis was known as the inventor of the "Big Berthas" up through his death in June of 1917. Even the New York Times labeled Louis Gathmann as the inventor.