The Jews were punished with 70 years of exile for the 70 Shmita years (sabbatical years) they did not keep. (Chronicles II 36:21).
Does this mean they never kept Shmita even during the time of the Beit Hamikdahs (The Temple)? Or is this perhaps not meant to be taken literally?
See Ezekiel 4 and Leviticus 26 and Rashi there for other references to the 430 years when Israel violated the Sabbatical and Jubilee years. Each Jubilee period, or 50 years contains seven Sabbaticals and one Jubilee for a total of eight years. In 400 years that would be 8 x 8 = 64 years violated. Another 28 years provides four Sabbatical for a total of 69. The 70th seven year cycle was counted against Israel even though it was not completed.
Now, the first Shmitta was observed 14 years after entry into the Land of Israel. Given that Israel was exiled after 850 years in the Land, less than half the Sabbatical and Jubilees were observed.
Erchin 13a-b goes through the calculations and seems to conclude that, indeed, they did not observe a single Shmittah during those 852 years.
