Answer:
What does a WW1 Trench, A Submarine and a Popular Phone App all have in common?
Late afternoons I often bathe. I'll soak in water piping hot. My essence goes through. My see through clothes. Used up am I - I've gone to pot.
I have an eye but cannot see, You'll head inside when you see me.
I march before armies, a thousand salute me. My fall can bring victory, but no one would shoot me. The wind is my lover, one-legged am I. Name me and see me at home in the sky.
What can touch someone once and last them a life time?
I am your mother's brother's only brother in law. Who am I?