1. British Army:
- Early Phase (1914-1915):
- Service Dress: Khaki serge tunic, breeches, and puttees (cloth wraps for the legs)
- Field Service Cap
- Later Phase (1916-1918):
- Khaki wool tunic and trousers
- Brodie steel helmet
- Respirator for gas protection
- Gas cape
2. French Army:
- Early Phase (1914-1915):
- Blue-grey tunic, red trousers (the famous "horizon blue")
- Adrian helmet
- Cloth puttees
- Later Phase (1916-1918):
- Dark blue-gray uniform (drab green for infantry)
- Adrian helmet
- Gas mask
3. German Army:
- Early Phase (1914-1915):
- Pickelhaube (spiked helmet)
- Field-grey tunic and trousers
- Leather or cloth boots
- Later Phase (1916-1918):
- Stahlhelm (steel helmet)
- Field-grey uniform
- Gas mask
4. United States Army:
- Early Phase (1917-1918):
- Olive drab wool uniform
- Campaign hat or "Montana peak" cap
- Leather puttees
- Later Phase (1918):
- M1917 "Doughboy" helmet
- Improved gas mask
5. Russian Army:
- Early Phase (1914-1915):
- Khaki tunic and trousers
- Papaha (fur hat) or peaked cap
- Leather boots
- Later Phase (1916-1918):
- Steel helmet (introduced in 1916)
- Khaki uniform
It's worth noting that as the war progressed, there were gradual improvements and changes in the design of uniforms, often driven by the need for better protection against new weapons and chemical warfare.