Bring 4 cups water to a boil with 1 cup sliced strawberries and 1/2 cup sugar; stir to dissolve the sugar. Remove from the heat, add 12 chamomile tea bags and steep 5 minutes. Strain through a fine-mesh sieve into a pitcher, gently pressing on the solids. Stir in 3 cups cold water and 1 cup gin. Chill. Serve over ice with strawberry slices.