The 'Dark Side' is the opposite to the 'Light Side' on that war winning bit of kit that used to be called 'Jungle Tape' or 'Black & Nastie' but is now just known as 'The Force'!
The 'Dark Side' provides strength and support required to repair everything from Combat Clothing to Tanks. It also provides a shiny surface ideal for writing on in Chinagragh pencil, making it useful for labeling people, kit and vehicles.
The 'Light Side' provides the sticky surface that will stick to everything whether you want it to or not. It is so sticky that even when you want to remove 'The Force', you may get rid of the 'Dark Side' but there will always be some of the 'Light Side' left behind.
Why is it now called 'The Force'? Well I don't know if it was the possible PC implications of using names which include the words 'Jungle' or 'Black', despite their innocent application. I think it's because of Star Wars..... there 'The Force' is used to achieve great things. But the main thing to remember is that "The Force has a dark side and a light side, and it holds the Universe together!"