Complex sentence: President Woodrow Wilson's administration announced successive plans for the expansion of the US Navy during 1916 and 1919 that, if completed, would result in a massive fleet of 50 modern battleships; currently it was engaged in building six battleships and six battlecruisers.
Split into simpler sentences: President Woodrow Wilson's administration announced successive plans for the expansion of the U.S. Navy from 1916 to 1919 that would have resulted in a massive fleet of 50 modern battleships. At the time, it was engaged in building six battleships and six battlecruisers.