This riddle is in season twice per year. Now is one of those times.
My first turns a harsh command into a start
And aid for a structure to aid from the heart.
Two of my second can take you quite far
And three of them help if locked out of your car.
My third is the final of a group of five
For which a newspaper reporter must strive.
My fourth counts the number of that which we share;
My fifth, twice the tour of a legionnaire.
Though you grow by my sixth again and again,
Your size is the same as it's always been.
My next two together, togetherness mean,
Yet on a map never together are seen.
If you attacked those heading into the bay,
My ninth is the word you most likely would say.
My last is a segment of distance that's put
Along with a meter, but never a foot.
My whole links the seasonal precipitation
With those who first gratefully made celebration.