Issue with Array assignment

Issue with Array assignment

I am having an issue with outputting an array. When I just output each
element without a for loop, the program runs fine. When I try to output
with a for loop, the program crashes the first time I set an element in
the array. I have marked the line where the program crashes when I
uncomment out the for loop. My sort seems to work fine and the program is
crashing way before that, so I'm pretty sure that isn't the issue. Any
ideas why the 2nd for loop would crash the program at the specified line?
int main()
{
int* Array;
int j = 5;
for(int i=0; i<5; i++)
{
Array[i] = j; //Crashes here with 2nd for loop uncommented
cout << Array[i] << endl;
j--;
}
Array = insertion_sort(Array);
cout << Array[0] << endl;
cout << Array[1] << endl;
cout << Array[2] << endl;
cout << Array[3] << endl;
cout << Array[4] << endl;
/*for(int k=0; k <5; k++)
{
cout << Array[k] << endl;
}*/
}