There are still two other sentences I need to rephrase. In particular, I need to simplify sentence 2.
1) Elizabeth wanted control of the immense markets which had been opened up by the discovery of America by Columbus in 1492 and the circumnavigation of Africa by Vasco da Gama in 1497. Can you say "She wanted to achieve the supremacy of the sea??)"
2) Charters and royal patents were conferred upon trade companies; exploration had royal support
1. Revise this sentence starting like this: Elizabeth wanted British ships to ...
2. OK - needs a period at the end.