march, marsh

March or march means to walk in military formation, with a measured step, or in a deliberate manner-
Forward, march!
We will all march in unison, down to the end of the parade ground.
March or march may also mean a demonstration, as for a political cause--
There will be a march on Saturday, to protest the new tax law.

Marsh or marsh means a swamp or wetland--
We saw a heron and some ducks at the marsh.
Part of the marsh has been made into a wildlife sanctuary.

Now that you know that,  you can say--
"We are going to march to the city hall, to ask for a new law to preserve the marsh as a park."

Note--"March" ( always capitalized ) means the third month of the year--
The weather begins to get warm in March.
There will be a holiday on March 1st.