The world was created on a day of the week, not a day of the year

The difference between the Israelite calendar and the calendar of other nations is the lack of a new year in the Israelite calendar. Typically, the gentile new year corresponds to the ostensible day on which the world was created. For the Israelites, that function is taken by the Sabbath day.

What has come to be called the new year is, in the Jewish calendar, the Memorial Day for a single army, thus uniting the entire nation in the honoring of those who fell in defense of the nation. Yom haZikaron unites the nation behind a single military as Yom haKippurim unites the nation behind a single clergy and a single sanctuary.

The sanctuary was that sacred institution most closely identified with the military.