Select Column From Table 2 If Not Exist On Table 1

I am trying to pull a min value of a date column from table 1, if table 1 does not have any record I need pull a date column from table 2. Table 2 will always have a unique record ID (No duplicate ID's).

Table 1

ID date
1 1/1/2014
1 1/5/2014

Table 2

ID date
1 1/5/2014
2 10/15/2014

Here is the desired result when running for ID = 1 (select Min(date) where ID = 1, I should be getting 1/1/2014 from Table 1.

If I am running the same query where ID=2 then I should be getting 10/15/2014 from Table 2. So basically I need to check if a value exists on Table 1 first, if there is no value on Table 1 and then to grab the value from Table 2.