Combine dates, water, and 1/4 cup sugar in a medium saucepan. Bring to a boil. Reduce heat, and simmer 5 minutes, stirring constantly. Remove from heat, and set aside to cool completely.
Cream butter in a large mixing bowl; gradually add brown sugar, beating well. Add egg; beat well. Combine flour, soda, salt, and cinnamon. Stir into creamed mixture. Cover and chill at least 1 hour.
Roll to a 16- x 10-inch rectangle on waxed paper; spread evenly with reserved date filling. Roll up jellyroll fashion; pinch ends to seal. Wrap in waxed paper, and chill overnight.
Cut into 1/4-inch slices. Place 3 inches apart on ungreased cookie sheets. Bake at 375° for 8 minutes or until lightly browned. Remove from cookie sheets, and cool on wire racks.